From our perspective, tracking sleep is not about measuring sleep itself, but rather what sleep produces: recovery of the mind and body. When you go to sleep, you’d think that your body powers down, but this is not the case at all. In fact, your body works all night long to restore and repair itself while you sleep.
Sleep – The 3 Stages
LIGHT sleep prepares your body for deep sleep. This is the time when your heart rate slows and your body temperature drops. DEEP sleep makes you stronger, faster and more durable. It literally heals you from the inside out. In deep sleep, your brain triggers the release of hormones that encourage tissue growth. As a result, you can recover from injuries, cuts for example, or sore muscles from training. REM sleep makes you smarter. You absorb numerous new things throughout the day, be it basketball plays and drills, school homework or stuff at work. Your brain sorts through all that new info while you sleep, and to be more exact, when you’re in REM sleep. Your brain decides what to store and what to toss.
I don’t know if you’ve seen the movie Inside Out, but it shows what happens during REM sleep; there are these (super cute) little guys working all night long inside your mind, going through your memories, battling it out and making decisions on whether or not a memory is important, and tossing all the unimportant ones in a memory landfill. That’s why for example pulling an all-nighter is not the best idea in the world. Instead of forcing it and trying to learn that basketball drill you couldn’t get the hang of at practice, go to sleep instead – chances are when you get on the court the following day, you’re able to do the drill.
As I mentioned earlier, the real reason to track sleep is to know more about recovery. You can do that by tracking REM and deep sleep to make sure your body and mind recover properly, but heart rate variability (HRV or RMSSD) is the next level thing to track. On the one hand, RMSSD evening values show how straining your day was. This is affected by stress that the mind and body experience during the day, such as training. Morning values, on the other hand, indicate recovery from this stress and strain during the night. Morning values also show the “condition of the day”, meaning readiness of your mind and body for the challenges of a new day ahead. It has been argued, according to important study results, that recovery might be the single most important indicator to predict favorable training adaptation. It may indeed be useful to use recovery (HRV) data to guide training decisions.
Tracking sleep and recovery over a short period of time is not very useful, but following long-term trends is valuable for both pro and recreational athletes. Evening and morning recovery values seem to be great indicators of fitness level. In order to get results, every athlete – no matter what level they’re at – needs recovery, the most neglected aspect of training; training and rest need to be in balance. Long-term trends are very helpful to keep on track. Too little recovery on the long-term will lead to an over-reaching state and if this continues, over-training becomes a threat. On the flip side, too much recovery doesn’t offer enough stress or stimulus to trigger physiological adaptation, leading to zero improved results.
How Much Sleep Do I Need?
Usually most people need 7-9 hours of sleep to feel well rested, happy and refreshed, but for athletes and those who are very active every day, the number can be a little higher. A great way to find out how much sleep you need is to do this little experiment I found on the Fitness Magazine. All you need is seven days on which you do NOT have to wake up early for work or anything else. Now that summer is coming up and there’s time to take a vacation you should have a perfect opportunity to do this! This is what you need to do:
- Go to sleep at the same time every night and mark down the times when you naturally wake up each morning (without an alarm).
- Calculate the amount of sleep on nights 4, 5 and 6, add them together and divide by three. The reason why you do not want to factor in the first three nights is because you may bee a little sleep deprived from the week before and need to do some catching up.
- Ta-da! The result you get is the approximate amount of sleep you need to feel refreshed in the morning. After the experiment, to determine your bedtime, all you need to do is count back from the time you have to get up in the morning and chances are you’ll feel much better when you wake up.
- Note that you could also simply do this on Emfit QS!
Sleep is important because recovery of the mind and body happen during this time. On the one hand, you need REM sleep to recover mentally – to have a sharp mind and remember what you’ve learned, for example. Deep sleep, on the other hand, helps you recover physically, e.g. build stronger muscles. Evening values of recovery data let you know how hard the day before was and morning values tell you how much strain and stress you are ready to take in. Long term values offer a deeper understanding of your condition and fitness level: whether it’s improving or decreasing.
Aittokoski, Timo. CTO at Emfit
Ben Greenfield, How to truly know if you’re recovering from your workouts
Fitness Magazine, 4 Steps to answer the “How much sleep do I need?” question
National Institute of Neurological Disorders and Stroke, Brain Basics: Understanding Sleep
WebMD, The healing power of sleep