The ninth variable that I will be manipulating across a two week period to examine its impact on sleep is exercise. Using my Misfit Ray data, I will be seeing if doing over 10,000 steps a day will be better for sleep than doing less than 10,000 steps.
I will discuss what my data shows, how easy or difficult I found this strategy to implement, and what previous research says. These three factors will be combined for an overall score and grade on how useful exercise is at improving sleep quality.
HOW COULD EXERCISE HELP?
Homeostatic Pressure is one of the three primary variables that are responsible for proper sleep quality. It is also known as sleep debt, and it is something that builds up during the day regardless of what we do unless we have a nap during the day or fall asleep at night. It is what TAC talks about in their latest ad ‘Drowsy Driving – You Can’t Fight Sleep’:
I have some clients with insomnia who would disagree with this ad because they manage to fight sleep every night. The difference with falling asleep on the road and in bed is the intent though. A driver who is trying to stay awake will drift off to sleep, and a person who is working hard to fall asleep in bed will stay awake. The reason that most people with insomnia can’t sleep is due to hyper-arousal rather than sleep pressure, and they are more likely to benefit from winding down before sleep or meditating rather than exercising more.
Exercise, as long as it isn’t done in the 3 hours before sleep, is meant to be great for our health, stress levels and sleep pressure. Essentially doing anything cognitively or physically demanding during the day can increase our sleep pressure at a faster rate, because it creates a greater need for restoration and recovery. Exercise can therefore potentially help us to feel sleepy earlier and have a better night’s sleep.
I’ve definitely had days where I have been extremely active, either from hiking all day to Mt Feathertop or playing a Beach Volleyball tournament. On these rare occasions, I’ve been extremely exhausted and have subsequently crashed before 10pm and slept over 9 hours. It will be interesting to see if these are one-offs, however, or if doing a bit more exercise each day really could help.
I’m generally pretty active and also play organised sport three times a week. Rather than trying to stop exercise altogether, what I’ve decided to do is monitor my steps each day using a Misfit Ray activity tracker, and compare the 7 most active days to the 7 least active.
If I wanted to be even more thorough, I could look at the data for the entire year, but I’ll just keep it to these two weeks for now and compare it to what the scientific research and literature says about sleep and exercise.
Comparison: Over 10,000 steps to under 10,000 steps
Based on my sleep diary data, the average of the more exercise week was 11,985 steps in comparison to the less exercise week average of 5852 steps. This means I did more than twice the amount of steps on the active days than the non-active days, which should be enough to see if more exercise makes a difference.
In spite of this, doing more exercise actually led to more awakenings per night, less time in bed, 30 minutes less sleep per night, and bedtime that was 33 minutes later than when I exercised less.
What exercise did seem to help with was time awake in bed, as I fell asleep 4 minutes quicker, spent 2 minutes less awake during the night, and had a better sleep efficiency.
My sleep quality was rated as precisely the same (4.14/5) regardless of how much exercise I did, with both a 3,552 step and a 15,180 step day obtaining a sleep quality rating of 5/5, and both a 4,456 and a 10,486 step day obtaining a sleep quality rating of 3/5. It appears that other things are more important to sleep quality than exercise.
Based on the Misfit Ray data, the depth of my sleep had no real relationship with the amount of exercise that I did.
Let’s compare the Sunday night from the first week (May 08 on the Misfit data – 7/5/17 on the sleep diary), where I did 13,410 steps the day before, to the Friday night of the first week (May 13 on the Misfit data – 12/5/17 on the sleep diary), where I did 4,456 steps the day before. If you were to look just at this, you could say exercise improves objective sleep quality.
However, my best night of sleep for the two week period was the Thursday of the second week (May 19 on the Misfit data – 18/5/17 on the sleep diary), where I only did 3,552 steps. This was the least steps on any day for the entire two weeks, and the best objective sleep, with a restful:light sleep quality ratio of 4.01:1. This is one of my best sleeps for the year, and all I could put it down to was an exhausting day at work.
IS EXERCISING MORE A GOOD SLEEP STRATEGY?
IS IT EFFECTIVE?
Maybe. I didn’t compare it to no exercise at all, and I still slept fairly well for the whole two week period, but doing more exercise than normal didn’t really seem to have much of an additional benefit for me.
I, therefore, give the effectiveness of this strategy a 16/25.
CAN IT BE APPLIED?
Yes, but with how time poor we all are these days, mostly thanks to our increased screen time in red in the graph below by Adam Alter, it might be hard to justify spending more time exercising if your only reason to do it is so that you can get better sleep.
If you are exercising with others for social interaction or for better overall health than that is a different story, but it is still important for each of us to determine how we’d like to spend the minimal personal time that we have, as indicated by the white and yellow in the graph above.
Only 30 minutes five times per week is enough to have a positive benefit on mood, so I’ll give the applicability of this strategy a 15/25.
IS IT SCIENTIFIC?
A 1996 Meta-Analytic review of the effects of exercise on sleep by Kubitz and colleagues said that a lot of the research has conflicting results and interpretations. With their re-analysis, they found that both acute and chronic exercise can help people to fall asleep faster, sleep longer and obtain more deep sleep. The negative of exercise is that is reduces rapid eye movement (REM) sleep, which is useful for emotional processing and learning.
Another review by Taylor and Driver (2000) indicated that exercise “can be beneficial to general well-being but may also stress the body”, which means that it shouldn’t be done too close to bedtime. They also said that even though some modest effect sizes have been found, “the sleep-promoting efficacy of exercise in normal and clinical populations has yet to established empirically” (Taylor & Driver, 2000).
A 2008 study by King and colleagues found that a 12-month moderate-intensity endurance exercise program in older adults reduced their amount of stage 1 sleep, increased their stage 2 sleep and reduced their awakenings during the first third of a polysomnography study. Participants in this study also subjectively reported falling asleep quicker each night, having fewer sleep disturbances, and feeling more rested in the morning (King et al., 2008).
A 2010 study by Reid and colleagues also found that sedentary adults over 55 with insomnia who began exercising aerobically for 16 weeks improved their subjective sleep quality, the time taken to get to sleep, total sleep time and sleep efficiency. Furthermore, they also experienced less daytime dysfunction and sleepiness and rated themselves as being less depressed and having more vitality than before they began the exercise program (Reid et al., 2010).
Because of all of the scientific benefits of exercise on health in general, as well as the modest benefits of regular exercise on sleep, I, therefore, give the science of this strategy a 30/50.
Overall, exercising more as a way to sleep better gets a score of 16/25 + 15/25 + 30/50 =
WHAT I RECOMMEND
A moderate exercise regime of both cardio and strength training is going to be good for your health, but do see a doctor for a check-up first before beginning an intensive program. In the long run, regular exercise could lead to better sleep for you too. Just try not to engage in vigorous exercise in the last three hours before bed too often, as this can raise your arousal levels and make it harder to get to sleep at the start of the night.
If you are currently experiencing severe insomnia, increasing your exercise is probably not the first step that I would recommend taking, especially if you are already quite active and feeling exhausted before you go to bed each night. A better approach would be not spending too much time in bed, minimising your alcohol intake, staying off bright screens in the last two hours before bed, and doing things to wind down before sleep.
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