We tend to have more brain power following exercise and a good night’s sleep. But what aspect of sleep might explain the beneficial effects of physical activity on the brain? Is it sleeping longer that enhances mental prowess?
Authors of a new study think they know—and insomnia sufferers should take note.
Effects of Exercise on Sleep and Cognition
Research has shown that exercise—or physical activity in general—is beneficial to sleep. Physical activity helps people fall asleep quickly and sleep more deeply. It also tends to improve sleep efficiency, that is, it increases the amount of time in bed spent sleeping.
Exercise is also known to have positive effects on the brain. Physical activity enhances memory and the “executive control processes” that occur with activity in the frontal region of the brain. This part of the brain is responsible for planning, initiating, and monitoring complex mental and physical tasks.
Researchers at the University of Pittsburgh and the Georgia Institute of Technology were interested in these relationships. They wanted to know which aspect of sleep following exercise was associated with improved executive control, and whether there were differences between younger and older adults.
A total of 112 community residents participated in the study, 59 young adults (ages 21–30) and 53 older adults (ages 55–80). They went through two rounds of cognitive testing spaced one week apart. The cognitive testing involved several computer-based and pencil-and-paper tasks assessing working memory, task switching, verbal ability and fluency, and delayed recall of information.
Participants also wore an accelerometer armband during the week between the two testing sessions. Similar to sleep and activity trackers on the market today, the accelerometer monitored participants’ physical activity and their sleep.
Sleep Efficiency Rules
As expected, the more physically active participants performed better on the tests. The novel finding was this: what mediated, or facilitated, this relationship was not that the exercisers slept longer than their sedentary counterparts. It was that their sleep was more efficient. This was true for both younger and older study participants.
A Relationship Between Sleep Efficiency and Insomnia
So sleep efficiency seems to be an important aspect of sleep. If you’ve got chronic insomnia—if you experience trouble thinking and concentrating after nights of broken sleep—you’ll want to take note. Insomniacs’ sleep is often inefficient. Your sleep efficiency is low if you
- lie in bed awake for a long time before falling asleep,
- wake up several times during the night, or
- wake up in the middle of the night and take a long time to fall back to sleep.
Sounds familiar, right? In all these situations, you’re spending lots of time in bed lying awake rather than asleep. Your sleep efficiency is high if
- you fall asleep quickly, and
- your sleep is deep enough to remain solid and unbroken throughout the night.
When your sleep is efficient, you’re asleep most of the time you’re lying in bed and awake very little. This may not reflect your situation now, but it is something to work toward.
As the study above suggests, one way to improve your sleep efficiency is to get daily exercise. The authors’ “novel finding fits in line with the broad view that uninterrupted sleep may promote brain health and that this process may be facilitated through physical activity.”
There are also insomnia treatments that increase sleep efficiency. One was in the news recently, and I’ll write about it in next week’s blog post.
Does regular exercise have any effect on your sleep? If so, what is it?