What Science Really Says About Exercise and SleepHeather Neal
I never really put much thought into sleep until I didn’t do much of it for 8 straight months as a new mom. 10 months later and I think I’m still recovering. It wasn’t until I was beyond a state of chronic sleep deprivation that I realized how truly important it is. I felt awful, I couldn’t think straight, my skin looked sallow, and I felt physically incapable of doing anything more than a short walk.
After months of not going to the gym because I was “too tired,” I’d had enough. It didn’t look like I’d get a good night’s sleep anytime soon, so it was time to shove my excuse — although valid — aside and start working out again. I needed whatever mental boost I could get!
Imagine my surprise when I woke up a couple weeks after getting back in the gym feeling refreshed. Nope, my baby didn’t magically start sleeping through the night. So why did I feel a little bit of my old pep returning? Turns out, exercising was helping me get a better night of sleep. As I kept up my routine, my workouts were improving: I was working out harder and recovering faster.
Sleep researcher Dr. Kelly Baron states the relationship between exercise and improved sleep in a fairly matter of fact, simple manner: “You work out, fatigue your body and mind, and sleep more soundly that night.” A poll from the National Sleep Foundation revealed that exercisers reported a better night’s sleep on days they exercised, regardless of intensity. However the study also revealed that vigorous exercisers are more than twice as likely to say they had a good night’s sleep as non-exercisers.
Some studies, however, have shown that it takes more like 4 months of a steady exercise program for people with sleep disorders, like insomnia, to obtain this same effect of exercise and sleep. One study showed that after a group of insomniacs exercised 30 minutes 3 times per week over 16 weeks they were sleeping 45 minutes to an hour more each night.
During her study Dr. Baron stumbled upon a surprising result: The previous night’s sleep was affecting the next day’s exercise performance, more than the amount of exercise was influencing sleep. She found that a poor night’s sleep led to a shortened exercise session the next day, but a full length workout didn’t lead to good sleep that night.
So whether or not I could attribute my improved sleep to exercise remains to be proven. But what about the improvement in my workouts? Was that because I was working hard, or was it because I was sleeping better?
In addition to Dr. Baron’s findings that sleep can affect exercise, some state that sleep is vital to workout performance because it gives the body a chance to recover. According to the National Sleep Foundation, Stages 3 and 4 of sleep, which is when the deepest sleep occurs, allows the blood flow to your muscles to increase, and your body is able to rebuild and repair tissues. Growth hormone, which is important for muscle building, is also released during this phase of sleep. WebMD says going to bed an hour earlier or taking an afternoon nap can improve performance whether you’re an Olympic athlete or a weekend warrior. David Geier, MD, Director of Sports Medicine at the Medical University of South Carolina, puts the idea in terms many of us can relate to, saying, “Just as athletes need more calories than most people when they’re in training, they need more sleep, too.”
Research has even shown sleep deprivation to hinder reflexes. One study showed basketball players who increased their sleep by 2 hours improved their speed by 5% and their shooting accuracy by 9%. Another study showed that sleep deprivation increases the amount of cortisol (the stress hormone) the body releases, which impairs muscle recovery. Lack of sleep also leads to impaired glucose metabolism and glycogen synthesis, which is just a fancy way of saying the ability to store energy was lowered.
So as if you needed another reason to sleep more, it might make your workout a little more effective. At the least, a workout may help you sleep better. Now how to find the time for that extra hour of sleep…