July 18, 2016
I'm on a constant quest to determine how elements such as air, light, electricity, water, food, movement and more affect important variables such as a performance, fat loss, recovery, digestion, brain, sleep and hormones.
So I was understandably a bit excited when I discovered the ŌURA ring at a biohacking conference in Finland. This small, stylish ring promised to use state-of-the-art miniaturized electronics to track and measure a host of parameters, including sleep, heart rate, heart rate variability (HRV), activity, body temperature, movement, respiration, and more.
I decided to find out more about this thing, so in the podcast “Could This New Ring Be The Final Frontier In Self Quantification, Biohacking, Sleep Tracking, HRV, Respiration & More?“, I interviewed the Co-Founder and CEO of ŌURA ring: Petteri Lahtela. During our discussion, we talked about:
-How the ŌURA ring identifies deep sleep, REM sleep, light sleep, and periods of wakefulness, and how accurate this data is compared to actual sleep lab measurements…
-Why the ŌURA ring is designed to allow you to completely disable the bluetooth function, and why the ring is specifically designed to not constantly transmit a signal (very important if you are concerned about electrical pollution)…
-The infrared measurement used to analyze HRV, and why it is just as accurate at measuring HRV as wearing a chest strap…
-How the Readiness Score you get from the ŌURA ring helps you identify days that are ideal for challenging yourself, and those that are better for taking it easy…
-How something called your interbeat interval and pulse waveform can be used to accurately calculate your respiration rate…
-The important data that you can collect about your body using the built-in accelerometer inside the ring…
-How the ŌURA measures temperature, and what kind of health information you can discover by monitoring your body’s temperature…
-Why the ring was designed to withstand extremes of environment and temperature, such as hot saunas, cold water, etc.
-How you can use the ring to track daily consumption (caffeine, alcohol, sugar), sleep aids you might be trying (valerian, melatonin, acupuncture) or other factors in your environment (barometric pressure, CO2, pollen count) using something called the Curious platform…
-And much more.
Anyways, you can click here to listen to that podcast…
…but since releasing that episode and subsequently getting myself an ŌURA ring, spending oodles and oodles of hours testing it, putting it through ringer (yes, a pun) and pouring over the data, I've generated a big list of my own questions and also received plenty of questions from listeners and readers like you about how to interpret and make sense of data generated by self-quantification devices.
So in this article, I'm answering 11 of the most crucial questions I've received, and you're going find out everything you need to know about parameters that drastically affect the way you look, feel and perform, but parameters you don't see talked about much these days, things like…
…”lowest resting heart rate during sleep”…”activity readiness score”…”brain pulsations” and beyond. Even if you don't own a self-quantification device, this article is going to be an information-rich resource for you to read, bookmark and use in your own pursuit of a perfect combination of sleep, activity and full body readiness for anything life throws at you.
Leave any additional comments below the post and I'll ensure you get your question answered. Also mention my name in the comments section of any order for an ŌURA ring and they'll knock $10 off after you order, whether USA or International.
Q. What is a “Sleep Score” and what kind of things contribute to it?
A. Ranging from 0-100%, your Sleep Score is simply an overall measure of how well you slept. That's it. A Sleep Score of 85% usually means that all contributors are in balance, and you meet the typical sleep needs of a person your age. Of course, sleep needs vary from person to person, so it's good to evaluate and interpret your Sleep Score in relation to your feelings and performance level. If you feel refreshed in the morning and energetic throughout the day, your Sleep Score is most likely at a good level.
So what are the most important variables that affect this Sleep Score?
-Total sleep: Total sleep refers to the total amount of time you spend in light, REM and deep sleep. The amount of sleep needed varies from person to person. As a general rule, the younger you are, the more sleep you need. Most adults need 7-9 hours to perform well and stay healthy. Getting a good amount of sleep for your age will keep your Total Sleep time in balance, approximately at 80%. If you're using the ŌURA ring to measure your sleep, you will see a full bar when your Total Sleep time reaches 9 hours.
-Efficiency: Sleep efficiency is a measurement of your sleep quality. It's the percentage of time you actually spend asleep after going to bed. For adults, a generally accepted cut-off score for good Sleep Efficiency is 85%. It's common for Sleep Efficiency to slightly decrease with age. For a maximum positive contribution to your Sleep Score, your Sleep Efficiency needs to be 95%. You'll see a lowered Sleep Score if it has taken more than 20 minutes for you to fall asleep, or if you experience one long or multiple shorter wake-ups during the night.
-Disturbances: Sleep Disturbances caused by wake-ups, get-ups and restless time during your sleep can have a big impact on your sleep quality and daytime cognitive performance. Restless sleep is less restorative than uninterrupted sleep, and it's usually the cause of daytime sleepiness. Disturbances can be caused by various different factors, such as stress, noise, partners, pets or different foods. To improve your chances of getting restful sleep, read my article on 4 ways to hack your sleep cycles.
-REM Sleep: REM (rapid eye movement) sleep plays an essential role in re-energizing your mind and your body, making it an important contributor to your sleep quality. REM is associated with dreaming, memory consolidation, learning and creativity. Making up anywhere between 5-50% of your total sleep time, the amount of REM can vary significantly between nights and individuals. On average REM counts for 20-25% (1,5h – 2h) of total sleep time for adults, and it usually decreases with age. REM is regulated by circadian rhythms, i.e. your body clock. Getting a full night’s sleep, sticking to a regular sleep schedule and avoiding caffeine, alcohol or other stimulants in the evening may increase your chances of getting more REM.
-Deep Sleep: Deep Sleep is the most restorative and rejuvenating sleep stage, enabling muscle growth and repair. When you're in deep sleep, your blood pressure drops, heart and breathing rates are regular, arm and leg muscles are relaxed and you're very difficult to awaken. Varying significantly between nights and individuals, Deep Sleep can make up anywhere between 0-35% of your total sleep time. On average adults spend 15-20% of their total sleep time in Deep Sleep, the percentage usually decreasing with age. Regular physical activity, avoiding heavy meals and alcohol before bed and long naps and caffeine in the afternoon can improve your chances of getting more Deep Sleep.
-Sleep Latency: Sleep Latency is the time it takes for you to fall asleep. Ideally falling asleep shouldn't take more than 15-20 minutes. Falling asleep immediately (in less than 5 minutes) could be a sign that you're not getting enough sleep for your needs. If you have trouble falling asleep, try getting out of bed and doing something relaxing, ideally in low light conditions, until you feel sleepy again.
-Sleep Timing: Your Sleep Timing is an important contributor to your sleep quality and daytime performance. Most of your body’s essential processes such as your body temperature, hormone release and hunger run in 24-hour cycles called circadian rhythms. Sleeping during the night and staying awake and active during the day can help keep these internal rhythms in balance, and helps you perform better throughout the day. For example, the ŌURA ring algorithm considers your Sleep Timing to be optimal and aligned with the sun when the midpoint of your sleep falls between midnight and 3 am, allowing some variability for morning and evening types. A timing significantly earlier or later can lower your Sleep Score.
And then there's my personal favorite: the lowest resting heart rate during the night. More on that below…
Q. Why should I know when my lowest resting heart rate occurs during the night?
A. As you probably already know, your Resting Heart Rate (RHR) is the number of times your heart beats per minute when you're at rest. It's a good measurement of your sleep quality, recovery and overall health. But ŌURA measures your heart rate throughout the night and displays the lowest 10-minute average it has detected. Normal RHR during the night for adults can range anywhere from 40-100 BPM (mine is 35, but I'm an endurance freak, and if you're a swimmer, cyclist, runner, triathlete, etc. then this may be the case for you too). The best way to determine your normal level is by looking at your own data history.
This lowest RHR during the night is affected by various factors, such as physical activity, nutrition, body position, and environment. A low RHR is often associated with good fitness and overall health. An exceptionally high or low RHR is usually a sign of increased need for recovery, and here's the important thing: if your lowest resting heart rate occurs during the night at a later time than usual, that can be a sign of an increased need for recovery or that you are sleeping at too high a temperature in your room.
Good to know, eh?
Your RHR can be elevated after a late night workout, a heavy meal in the evening, or when your body temperature is higher than your average. For women, the menstrual cycle can cause a small increase in RHR during the second half of the cycle (ovulatory and luteal phases).
It’s also normal for your RHR to be higher than usual when recovering from an intense training day. As you increase your training volumes and your fitness improves, your RHR and your lowest RHR during the night should start to decline over time.
Q. What kind of things should I think about tracking in terms of what affects my sleep in a good or bad way?
A. Exercise is a good first place to start. Data suggests not only that exercising during the day will help you fall asleep more quickly and plunge you into deeper sleep for a longer period of time, but also that exercising causes your body to produce growth hormones, which help it to repair and revitalize itself. Many people report that based on sleep tracking results they sleep better with regular exercise and that they feel more alert and rejuvenated the following day.
Diet is of course another key variable to track. Check out this excellent article to see the findings of sleep studies in relation to diet. For example, one study states:
“The midpoint of sleep is significantly associated with dietary intake of certain nutrients and foods and other dietary behaviors in young Japanese women. This finding may contribute to consider the relationships between chronotype and dietary intakes and behaviors.”
This is especially true for those who are sensitive to gluten (like I am) or some other foods without knowing it will have big effect on sleep and restorativeness of sleep. Also soft drinks and other drinks sweetened with fructose and/or artificial sweeteners extensively affect liver function and therefore disturb sleep, especially between 1am and 3am.
Then there is caffeine, alcohol and other stimulants and depressants. The “half-life” of a compound, which is the level at which the effect of these type of stimulants or depressants is somewhat reduced tends to vary widely based on genetics, metabolism, etc.. Many of them prevent you from either falling asleep or having good quality sleep. For example, alcohol induces sympathetic activity of autonomic nervous system, increases resting heart rate, delays the reaching of the lowest resting heart rate, increases body temperature, blood pressure, insulin levels, dehydrates the body and for any of those reason awakens you some time in the middle of the night. In general, many stimulants taken too near to sleep time practically limit the restorativeness of sleep and cause sleep debt (deprivation). It can actually take several nights of sleep and balancing daily behavior to recover both mentally and physically from one poorly slept night.
As you track these kind of variables in relation to your sleep quality, try the following:
-First, stick to a regular bedtime and wake-up time before starting other hacking experiments – this needs to be preferably a week or longer and the the time when you reach the lowest resting heart rate (RHR) during the night should not change too much.
-If the lowest RHR happens late in the night or more in the morning then you have not recovered well from either having too intensive activity late in the evening or you have had too full meal late in the evening or taken stimulants or spent too much time too late on blue light (screen time), for example. All of these mess up the sleep pattern and sleep becomes lighter.
-Pay attention to wake-sleep cycle and circadian alignment (reflected in skin temperature being clearly higher during the night than the day – which can also be checked from the ŌURA report)
-Pay attention to not only the amount of deep sleep but overall sleep architecture and sleep score that ŌURA gives you, since the overall picture is more important. Also, the balance of activity, timing and intensity in relation to sleep timing is very important. If the timing of lowest RHR varies continuously then there is something in your lifestyle, diet or rhythms that challenges your sleep.
Q. What is Sleep Timing?
A. Your Sleep Timing is an incredibly important contributor to your sleep quality and daytime performance. Most of your body’s essential processes such as your body temperature, hormone release and hunger run in 24-hour cycles called circadian rhythms. Sleeping during the night and staying awake and active during the day can help keep these internal rhythms in balance, and helps you perform better throughout the day.
The ŌURA ring considers your Sleep Timing to be optimal and aligned with the sun when the midpoint of your sleep falls between midnight and 3 am, allowing some variability for morning and evening types. A timing significantly earlier or later can lower your Sleep Score.
So what kind of things can affect Sleep Timing (AKA circadian rhythms)?
One big factor is “social jetlag”. Millions of people today force their bodies to adjust to artificial sleep schedules, negatively affecting both their sleep and their health. Sleep jetlag is actually a new term for this, as you can see from the anecdote below taken from this study:
“Humans show large differences in the preferred timing of their sleep and activity. This so‐called “chronotype” is largely regulated by the circadian clock. Both genetic variations in clock genes and environmental influences contribute to the distribution of chronotypes in a given population, ranging from extreme early types to extreme late types with the majority falling between these extremes. Social (e.g., school and work) schedules interfere considerably with individual sleep preferences in the majority of the population. Late chronotypes show the largest differences in sleep timing between work and free days leading to a considerable sleep debt on work days, for which they compensate on free days. The discrepancy between work and free days, between social and biological time, can be described as ‘social jetlag.’”
Sleeping and waking time also has effect on circadian rhythm. For example, your drive for sleep increases as a function of time elapsed since your awakening. A normal, regular sleep-wake time works as regulator for circadian drive for alertness, balancing and improving your sleep quality. Circadian drive for alertness peaks at the end of circadian day and reaches its peak at the end of circadian night, and this means that in an ideal situation, you should go to bed and wake up at similar times each night and day.
Meal time is another huge cue for your circadian rhythm. Clocks in your peripheral tissues are actually governed by feeding cycles. Thus, diurnal feeding imposes diurnal rhythms upon all these tissues in your body (Mohawk et al., 2012. Central and peripheral circadian clocks in mammals, Annu. Rev. Neurosci. 35 (2012) 445e462.). That study shows that chronic advances in light-dark cycles imitate jet lag and shift work, increase body weight and alter the expression of metabolic genes, whereas time-defined feeding prevents obesity without affecting caloric intake.
Yes, these results suggest that the major factor involved in obesity induced by jet-lag or shift work is fluctuating meal timing and not a shift in light-dark cycles1
Typical methods used to measure circadian rhythm are melatonin levels and core body temperature. According to several studies the skin temperature is actually an accurate marker of the circadian rhythm. [Corbalan-Tutau et al., 2011; Ortiz-Tudela et al., 2010; Sarabia et al., 2009], and your sleep midpoint is good parameter for measuring your circadian rhythm too.
Q. How much time in each sleep phase should I get?
A. Let’s start with the first: REM sleep…
REM sleep is a unique phase of mammalian sleep characterized by random movement of the eyes, low muscle tone throughout the body, and the propensity of a sleeper to have vivid or lucid dreams. This phase is also known as paradoxical sleep (PS) and sometimes “desynchronized sleep” because of its physiological similarities to a waking state, including rapid, low-voltage desynchronized brain waves – basically a combination of alpha brain waves and beta brain waves.
During a typical night of sleep, you usually experience about four or five periods of REM sleep, which are quite short at the beginning of the night and longer toward the end. The first REM episode typically occurs about 70 minutes after falling asleep. Cycles of about 90 minutes each follow, with each cycle including a larger proportion of REM sleep. REM sleep typically occupies 20-25% of total sleep in adult humans, or about 90–120 minutes of a night’s sleep.
Here’s the important thing to look for when evaluating the “sleep percentage” your sleep-tracking device of choice gives you: REM sleep typically occupies 20-25% of total sleep in adult humans, or about 90–120 minutes of a night’s sleep. That’s the number you should be shooting for.
Next comes non-REM (NREM) sleep, which is best defined as any sleep not recognizable as REM sleep. NREM consists of three separate stages: stage 1, stage 2 and stage 3, also known as N1, N2 and N3 – with N1+N2 typically being classified as light sleep, and N3 being classified as deep sleep.
Stage 1 (NREM1 or N1) is the stage between wakefulness and sleep, sometimes referred to as “drowsy” sleep, in which your muscles are still quite active and your eyes roll around slowly, and may open and close from time to time. In more scientific terms, stage 1 is the period of transition from relatively unsynchronized beta and gamma brain waves (with a frequency of 12-30 Hz and 25-100 Hz), which is the normal range for the awake state, to more synchronized but slower alpha waves with a frequency of 8-13 Hz, and then to theta waves with a frequency of 4-7 Hz.
During N1 sleep, your breathing gradually becomes more regular and your heart rate begins to slow. Dreaming is relatively rare during this stage, but sudden twitches or jerks (sudden short micro-awakenings) are quite common, and these are simply the last gasps of waking control before sleep fully takes over. During this short period of very light, easily disrupted sleep, which usually lasts less than 10 minutes, you can be aware of sounds and conversations, but you feel unwilling to respond to them.
Typically, this stage should represent only about 5% of your total sleep time.
Stage 2 (NREM2 or N2) is the stage of sleep in which muscle activity decreases still further and conscious awareness of the outside world begins to fade completely. Brain waves during stage 2 are mainly in the theta wave range (just like N1 sleep), but N2 sleep is also characterized by two distinguishing characteristics: sleep spindles (short bursts of brain activity in the region of 12-14 Hz, lasting maybe half a second each, also known as “sigma” waves) and K-complexes (short negative high voltage peaks, followed by a slower positive complex, and then a final negative peak, with each complex lasting 1-2 minutes). Together, these two waves protect sleep and suppress response to outside stimuli, as well aid in sleep-based memory consolidation and information processing.
Because you pass through this stage several times during the night, more time is spent in stage 2 sleep than in any other single stage, and N2 should typically constitutes about 45%-50% of total sleep time. If you add up N1 (ideally 5%) and N2 (ideally 45-50%), that is what something like the ŌURA will quantify as total light sleep, so now you know that total light sleep should be around 50-55% on a sleep quantification reading.
Finally, stage 3 (NREM3 or N3) occurs, and this known as deep or delta or slow-wave sleep (SWS), characterized by delta brain waves with a frequency of around 0.5-4 Hz. During this stage, you are even less responsive to the outside environment, essentially cut off from the world and unaware of any sounds or other stimuli. Neuronal activity, brain temperature, breathing rate, heart rate and blood pressure are all at their lowest levels during stage 3 sleep. Dreaming is more common during this stage than in the other non-REM sleep stages, and this is also the stage during which “parasomnias” such as night terrors, sleep-walking, sleep-talking and bedwetting occur. Information processing and memory consolidation also take place during this stage.
Interestingtly, it is much more difficult to wake a person during stage 3 sleep, and if awakened at this stage, you will often feel very groggy. It can take up to 30 minutes before they attain normal mental performance (known as sleep inertia). Hence the advent of many new alarm clocks and self-quantification devices that sync to your phone or cause a vibration or alarm to occur during the point in the morning when you are not in this stage of sleep (I think that’s a quite handy feature).
This stage 3 sleep (AKA “deep sleep”) should ideally represent around 15%-20% of your total sleep time.
OK, so let’s review what kind of percentages you should be looking for when analyzing your sleep data:
-Awake time should be 1-5%
-REM sleep should be 20-25%
-Light sleep should be 50-55%
-Deep sleep should be 15-20%
As you learn in my podcast with sleep expert Nick Littlehales, you should ideally go through four to five of these sleep cycles from REM to NREM during any 24 hour period, or about 35 sleep cycles every week.
Q. What if my sleep tracking device shows I get really low levels of deep sleep?
A. Surprisingly, your sleep can be good even if you don't get very much N3 (=deep) sleep. Even in brain wave signals, deep sleep can be deeper or lighter in one person over the course of the night, and between people. In the sleep lab, depending on the low frequency brain wave signals at certain cut-point sleep is determined as N2 (light) instead of N3 (deep). By the way, the term “light sleep” (as N2 has been called historically together with N1) is actually not the best word to describe N2, because stage 2 N-REM sleep is actually the very “base” sleep stage and restorative as well.
There is certainly some inter-individual variability in how breathing and HRV characteristics and the exact number of motions allowed for the point where N3 starts and N2 ends. Now, assuming somebody makes behavioral adjustments and wishes to see if they start getting more deep sleep, can they be sure that something like the ŌURA ring will show the changes? The answer is yes, because the ŌURA will react to changes when more N3 starts to accumulate. There is some quantification challenge if sleep only deepens a little (doesn't reach the criteria set for deep).
It seems that many people who see they are getting low levels of deep sleep tend to start doing some extensive hacking for getting more deep sleep but many times the most powerful hacks are actually very simple. For example, you can see some interesting stats by plotting bedtime start times against amount of deep sleep as well as the stability of your bedtime starts over past few days against your deep sleep. This indicates that the regular bedtimes and wake up times help keeping the circadian alignment and help the body learn the rhythm over the time. That leads to more stable sleep patterns and eventually to adequate amounts of deep and REM sleep as well. Your body tends to keep the rhythms and if they vary a lot, the sleep becomes lighter.
Then there's Heart Rate Variability (HRV), and how that relates to various sleep stages. I asked ŌURA if they planned on releasing much data regarding HRV during the night, and here was their reply:
“We will soon have great data about HRV in different sleep stages, which is reflecting the overall restorativeness better than morning HRV (http://circ.ahajournals.org/content/91/7/1918). Morning HRV mostly reflects the overall restorativeness of sleep and state of recovery but in the context of sleep stages it correlates more with the amount of REM. The HRV characteristics varies a lot in relation to sleep stages and therefore also measuring HRV “randomly” overnight does not provide much meaning….”
Which brings me to another point: I am constantly in touch with the folks at ŌURA, giving them feedback about the ring, the need for even more HRV functionality and “geeked out info” for nerds like me who want to tear into every shred of data, more napping sleep cycle info, etc. It's actually quite cool to see the app continue to evolve based on my own personal feedback.
Q. What are sleep pulsations, and why are they important with regards to sleep and recovery?
A. Recently scientists have developed a means to to monitor the actual pulsation of the blood vessels in the brain. These pulsations are how your brain “cleanses” itself while you sleep. Researchers have developed a specific MRI in which the brain is photographed 10 times per second, from which it is possible to see any disruptions in the cleansing system.
They detected three types of physiological mechanisms affecting cerebral cerebrospinal fluid pulsations: cardiac, respiratory, and very low frequency pulsations. Since glymphatic system failure may precede protein accumulations in diseases such as Alzheimer's dementia, this methodological advance offers a novel approach to image brain fluid dynamics that potentially can enable early detection and intervention in neurodegenerative diseases. The changes may appear years before the first symptoms of a memory and behavioural diseases and it may be possible in future to prevent diseases or treat them before any long-lasting effects on the brain.
The ŌURA ring accurately detects the characteristics in body signals that associate with different sleep stages, like the regularity of breathing, restfulness, characteristic patterns in blood volume pulse wave, pulse amplitude variation, resting heart rate and variation of the heart rate. Additionally ŌURA measures and provides long term trends of multiple body signals and parameters that indicate how your body responds to your daily life choices, rhythms and activities, among others. So, in addition to holistic view on sleep ŌURA provides a view on autonomic nervous system balance. ŌURA can be used 24/7 continuously and therefore enables longitudinal access to such sleep related insights in the context of normal daily life. This has not been possible before in this level of comfort and accuracy as a longitudinal view.
Q. What is a “Readiness Score”?
A. Ranging from 0-100%, the Readiness Score given by the ŌURA helps you identify the days that are ideal for challenging yourself, and those that are better for taking it easy. The Readiness Score is affected by a variety of “Readiness Contributors”, which help you to evaluate how well your recent and cumulative sleep, activity and recovery are in balance.
A Readiness Score above 85% indicates that you're well recovered. A score below 70% usually means that an essential Readiness Contributor, such as your body temperature or previous night's sleep, falls outside your normal range, or clearly differs from recommended, science-based values.
So what are the most important variables that affect readiness?
-Previous Night's Sleep: How you slept last night can have a significant impact on your readiness to perform during the day. Getting enough good quality sleep is necessary for physical recovery, memory and learning, all part of your readiness to perform. For a maximum positive contribution to your Readiness Score, your Sleep Score needs to be above 88%, and at the high end of your normal range.
-Sleep Balance: Sleep Balance shows if the sleep you've been getting over the past two weeks is in balance with your needs. Sleep Balance is based on a long-term view on your sleep patterns. It's measured by comparing your total sleep time from the past two weeks to your long-term sleep history and the amount of sleep recommended for your age. Typically adults need 7-9 hours of sleep to stay healthy, alert, and to perform at their best both mentally and physically. Insufficient sleep can eventually lead to sleep debt. Paying back sleep debt and rebuilding sleep balance takes several nights of good sleep.
-Previous Day: our level of physical activity yesterday is one of the key contributors to your Readiness Score. When Previous Day is in balance and the contributor bar is at 100%, you’ll know you’ve balanced your need for activity and rest, and substituted a nice amount of inactive time with low activity. An exceptionally high amount of inactivity or activity leads to a drop in your Readiness Score. If your readiness is low due to intense training and increased Activity Burn, taking time to recover can pay off as improved fitness.
-Activity Balance: Activity Balance measures how your activity level over the past days is affecting your readiness to perform. A full bar indicates that you've been active, but kept from training at your maximum capacity. This has boosted your recovery and helped build up your energy levels. While easier days can have a positive effect on your readiness level, challenging your body every now and then by increasing your training volumes helps maintain and develop your physical capacity in the long run.
-Body Temperature: ŌURA tracks the variations of your body temperature by measuring your skin temperature each night. Body temperature is a well-regulated vital parameter. When you sleep, ŌURA compares your skin temperature to similar measures from your earlier nights to estimate your normal range. A full contributor bar indicates that your estimated Body Temperature is within normal variation. You’ll see a lowered Readiness Score when your Body Temperature is outside your normal range.
-Resting Heart Rate: Resting Heart Rate (RHR) is the number of times your heart beats per minute when you're at rest. It's a reliable measurement of your recovery status, and an important contributor to your readiness. ŌURA evaluates the optimal level for your RHR by studying your data after active days and recovery days for a couple of weeks. Once it knows your normal range, your Readiness Score will start to become more accurate. ŌURA interprets a RHR slightly below your average as a sign of good readiness, whereas an exceptionally high or low RHR is a sign of increased need for recovery. An intense training day, a late night workout, elevated body temperature, or a heavy meal just before bed can keep your RHR elevated during the night, often resulting to a lowered Readiness Score.
-Recovery Index: Recovery Index measures how long it takes for your Resting Heart Rate (RHR) to stabilize and to reach its lowest point during the night. A sign of very good recovery is that your RHR reaches its lowest point during the first half of the night, at least 6 hours before you wake up. Alcohol, a heavy meal before bed or late exercise speed up your metabolism and keep your RHR elevated, delaying your recovery and increasing your sleep needs.
Q. What is an “Activity Score”?
A. Ranging from 0-100%, your Activity Score is an overall measure of how active you've been today, and over the past seven days. The Activity Score is affected by Activity Contributors. Before ŌURA starts collecting your personal activity data, the score is set by default at 75%. An Activity Score above 85% indicates that you're getting health and fitness benefits associated with increased physical activity.
For higher scores you need to reach your daily Activity Targets regularly, do medium and high intensity level training (Medium+) 3-5 times weekly, avoid long periods of inactivity and have 1-2 easy or recovery days weekly.
So what affects the Activity Score?
-Activity Burn. Activity Burn shows the kilocalories you've burned by daily movement and exercise. Activity Burn is an estimate of your net calorie burn. This means that it doesn't include your Basal Metabolic Rate (BMR), i.e. the calories your body would burn while resting. Activity Burn shows the additional calories burned by walking, training or doing other activities (the portion that exceeds 1.5 MET level). Tracking your Activity Burn can help you to balance out your current activity level and your calorie intake, which is key to good recovery and maintaining a healthy weight.
By the way, if you have no clue what a MET is, then read this for the nitty gritty details, but basically MET (or Metabolic Equivalent) is a common measure used to express the energy expenditure and intensity of different physical activities. If the MET value of a specific activity is 4, it means that you’re burning 4 times as many calories as you would burn while resting. The time engaged in different activities can be expressed as MET minutes. For example:
-30 min x 5 METs = 150 MET min
-30 min x 7 METs = 210 MET min
OK, let's keep going…
-Activity Frequency. Moving around and avoiding long periods of inactivity helps you stay healthy, and keeps your metabolism active throughout the day. ŌURA measures the time you’ve spent sitting, standing or otherwise inactive during the past 24 hours. Inactive time doesn’t include resting or sleep. Having 5-7 hours or less of inactive time per day has a positive effect on your Activity Score. ŌURA actually tracks the time you spend sitting, standing or otherwise passive, and guides you to break up long periods of inactivity. The number of continuous one-hour periods is displayed above the sitting icon in the Activity view. An hour of inactivity will only have a small effect on the contributor, but staying still for several hours will start to lower your Activity Score.
-Daily Targets: Each day ŌURA gives you daily Activity Target based on your age, gender and readiness level. Your daily activity is measured from 4 am to 4 am. Whether it's everyday activities or intense training, all daily movement measured during this 24-hour period moves you closer to your daily target. Meet Daily Targets will be at 100% when you’ve met your target on 6-7 days. Falling short of your target on 3 or more days starts to lower your Activity Score.
-Training Frequency: Training frequency measures how often you've gotten Medium+ activity over the past 7 days. Optimal Training Frequency is key to maintaining and developing your cardiovascular fitness. ŌURA recommends getting at least 100 MET minutes of medium+ activity a day. This is equivalent to 20 minutes of jogging or 30 minutes of brisk walking. Yep, that's not much. As you can read about here, I personally go way above and beyond that and target 15,000 steps per day, and the ŌURA algorithm is constantly being updated to allow for fancy “exceptions” to the activity score based on super active people like me.
-Training Volume: Training Volume measures the amount of Medium+ Activity you’ve gotten over the past 7 days. Like Training Frequency, Training Volume is an essential aspect of maintaining and improving your fitness level. For your Training Volume to have a maximum positive contribution to your Activity Score, you need to get 2000 MET minutes of Medium+ Activity per week (2000-3000 kcal, depending on your body weight). When your activity level goes below 750 MET minutes a week (750-1500 kcal), your Activity Score will start to decline.
-Recovery Time. As you probably know, having a sufficient amount of easier days in your training program boosts your performance and helps speed up your recovery. No matter how much you train, the actual fitness progress takes place during Recovery Time, when your muscles have time to repair and grow. For ŌURA, an easy day means keeping the amount of medium intensity level activity below 200 MET minutes (200-300 kcal/day depending on body weight), and high intensity activity below 100 MET minutes (100-150 kcal/day depending on body weight). In practice this can mean doing lots of low intensity activities, getting healthy amounts of medium intensity activity (e.g. 30-60 min), but only a small amount of high intensity activity (e.g. below 10 min).
The ŌURA ring gives you a minimum daily Activity Target based on your age, gender and daily readiness. When your Readiness Score is above 90%, your Activity Target is usually high. Days like these are usually optimal for taking your training to the next level and developing your physical performance. On days when your readiness drops below 70%, your Activity Target is lowered, and avoiding or reducing intensive training might be in order.
Q. Can I do weight training workouts and water workouts while wearing the ring?
A. Yes. For example, I do a huge number of pull-ups, swings, deadlifts, cleans, presses, etc. while wearing my ring, and for about the first 30 days of this, my inner pinky and inner middle finger went through the normal period of developing callouses on my finger skin from the ring rubbing. Now, just like any calloused area, there are zero skin issues on the finger.
The ring is also completely resistant and functional up to 50m deep in the water.
When you first order the ŌURA, you receive a sizing kit that ensures you get a ring that fits your finger perfectly. However, for situations such as Spartan races or triathlons that involve slippery mud, cold water, etc., I remove the ring so that I don't lose it.
Q. Is there a quick “cheat sheet” on these terms I can use for a reference?
A. Yep, here you go:
|Automatically detected by OURA
|Sleep helps to recover from accumulated mental and physical load. It is an active and dynamic state characterized by changes in brain activity and physiological function including breathing, heart rate, blood pressure, autonomic nervous system and body temperature.
|Sleep is divided into rapid eye movement (REM) and non-REM sleep types. NREM sleep is composed of three different stages ranging from very light to deep. Oura detects both NREM – light and deep – and REM sleep, as well as awakenings during the sleep.
very light (N1) and light sleep (N2) are combined
|Normal sleep architecture follows a cyclic pattern of sleep stages. A sleep cycle proceeds from lightest to deeper stages of NREM to the REM sleep and repeats itself about every 90 minutes. Sleep patterns can be affected by factors like age, the amount of recent sleep or wakefulness, the time of sleep, behaviors prior to sleep such as exercise, stress, jet lag, as well as environmental conditions such as temperature and light, and various chemicals.
|During light sleep person becomes disengaged from surroundings, eyes moves slowly or stop moving, muscles relax with occasional twitches, heart rate and breathing rate are lowered, and body temperature drops. During light sleep person is easily awakened by noises and other disturbances. About 50-60% of the sleep time is spent in the light sleep stage.
|Deep sleep is the deepest and most restorative sleeps stage. Blood pressure drops, heart and respiratory rates are low and regular, muscles are relaxed, energy is restored and essential hormones are released enabling tissue growth and repair. During deep sleep person is very difficult to awaken. Deep sleep is necessary for feeling well rested and energetic during the next day. Longest periods of deep sleep occur during the first half of the night. About 15-20% of sleep time is spent in deep sleep, and the amount declines with age.
|REM sleep is associated with dreaming. A short period of REM may occurs about 90 minutes after falling asleep, and longer periods of REM typically occur during the second half of the night. During REM, eyes move rapidly, breathing becomes rapid, shallow and irregular, heart rate and blood pressure increase and arm and leg muscles are temporarily paralysed. Typically 20-25% of the sleep is spent in REM sleep, and the amount slightly decreases with age.
|Time in Bed
|Time in bed starts when “the head hits the pillow” and ends at rise-up including awakening periods before falling asleep and during the sleep.
|Total Sleep Time
|Sleep duration, or total sleep time, is the amount of time spent in light, deep and REM sleep stages during the night.
|Sleep efficiency is the ratio between sleep duration and time in bed. Sleep efficiency over 85% can be regarded as normal, while a number below 70% can be considered to be very low. Difficulties in initiating or maintaining sleep diminish sleep efficiency.
|Sleep Onset Delay
|Sleep onset delay, or sleep latency, is the amount of time that elapses between the time the person’s head hits the pillow and the time person eventually falls asleep. Normal sleep onset delay is around 15 minutes. Very short sleep onset delay can be indirect indicator of sleep deprivation, while extended sleep onset delay is indicating difficulties of initiating sleep.
|Wake after Sleep Onset (WASO)
|WASO means time spent awake in bed after sleep has started, and before final awakening. It can be used to indicate the difficulties in maintaining sleep. The amount of awakenings increases the likelihood of feeling tired during the day, even though the tolerance for sleep disruptions varies. Sleep fragmentation seems to increases with age.
|Feeling drowsy during a day is a sign of not having enough sleep. If sleep is too short, the body doesn’t have time to complete all of the processes needed for muscle repair, memory consolidation and the release of the essential hormones. Sleep deprivation compromises cognitive, mental and physical performance. The sleep deprivation accumulated over several nights creates sleep debt. It may require several good nights to pay back sleep debt. For chronically sleep deprived it can take months to get back into the normal sleep pattern. Sleep debt that has been accumulated over extended periods of time may have irreversible negative consequences.
|Sleep Score is the parameter that shows your sleep quality at a glance. Oura Sleep score takes into account the positive and negative contributors for sleep quality such as total sleep time, REM and deep sleep duration, sleep onset delay and awakenings. Maximum Oura sleep score is 100% while 85% represents a level supposed to be adequate for normal daily performance. Individual tolerance to lower sleep scores may vary, but in general, lower sleep scores can be linked with impaired mental and cognitive performance and daytime sleepiness.
|Oura Readiness Score indicates the ability to perform in daily life. Most essential parameters contributing to the Readiness Score are preceding sleep and physical activity, accumulated sleep debt, nocturnal heart rate and body temperature.
|Chronotype refers to person´s typical time of sleep and ability to perform at different times of day. Morning type person wakes up early and is most active in the morning, whereas evening type person has later bed and wake-up times and is most energetic during afternoon and evening. Oura will utilize your daily rhythms and sleep related parameters in order to automatically learn about your chronotype characteristics.
|Several essential physiological and behavioral processes such as sleep-wake cycle, body temperature and hormone secretion follow circadian rhythms. An endogenous timing system generate and maintain circadian rhythms and is synchronized to solar rhythm mainly by external light stimuli. In addition, eating, sleeping, social behavior and physical activity synchronize the endogenous circadian rhythm. Misalignment between circadian and solar rhythms results in adverse consequences in many aspects of human health, including mental and physical performance, sleep, cardiovascular system, metabolic homeostasis and immune system. The target of Oura is to optimally align the endogenous and solar rhythms.
|Sleep Wake Cycle
|The sleep-wake cycle is regulated by an interaction and balance between two separate biological mechanisms in the body, homeostatic and circadian process. Homeostatic drive for sleep increases as a function of amount of time elapsed since last sleep episode and declines during sleep. The accumulation of sleep-inducing substances such as adenosine generates a pressure for sleep. The circadian drive for sleep peaks at the end of the biological night and reaches the lowest level at the end of the biological day. Adequate alignment between the homeostatic and circadian processes is crucial in obtaining optimal sleep and performance. Sleep-wake processes are influenced by the genes and several external factors such as medication, naps, mental and physiological strain and daily schedules.
I'd also highly recommend you listen to “Could This New Ring Be The Final Frontier In Self Quantification, Biohacking, Sleep Tracking, HRV, Respiration & More?“, if you want to learn more about the hardware in the ring, why it doesn't produce any electrical pollution, why it's drastically different than any other self-quantification device on the face of the planet and much more.
What do you think?
Do you already track or plan on tracking your sleep, readiness and activity?
Do you have questions about sleep cycles, activity readiness, or anything else I discussed in this article? Leave your comments and questions below, and I’ll reply. In the meantime, if you want to begin the process of self-quantification for yourself, you can…
Thanks for reading and happy tracking!