We all know what pulling an all nighter does to our ability to focus and mentally perform. It leaves you feeling wrecked the next day. That's what acute sleep deprivation does. It degrades your attention, memory, decision making ability - basically all the important stuff you need your brain to do. That’s the bad news. The good news is that you can recover quickly from these short term sleep losses. Your brain will increase your deep, slow wave sleep brain waves as much as 10% the next night to get you back on track. But what happens if your sleep loss isn’t one all nighter but night after night of partial sleep loss?
We adapt to exercise with bigger muscles. We adapt to sunlight with a tan (unless you had plenty of melanin to begin with). We adapt to skin friction with a callus - runners and guitar players will attest. Adaptation helps us handle that stress better in the future. And this is a good thing...usually. Sometimes your body will adapt in a way that is not desirable. When that happens we don’t call it adaptation anymore, we call it maladaptation - bad adaptation. This is what happens when we expose ourselves to chronic sleep restriction.
We understand it’s hard to put down that Blake Crouch thriller and of course, you can’t just watch half of an episode of Game of Thrones BUT chipping away at your sleep night after night will produce maladaptive changes in your brain. This study found changes can be apparent after only seven days of sleep restriction. Subjects demonstrated degraded reaction times even when the researchers restricted sleep to a generous seven hours. Cognitive performance suffered even more as sleep was restricted to shorter periods. However performance did not just keep plummeting. After a few days it stabilized which suggests that the brain had adapted. The restricted levels of sleep and the degraded cognitive performance that go with it became the new normal. When subjects in the study rated their sleepiness the ratings did not match their degraded cognitive performance. Again, this is likely because the brain adapts to long term sleep deficits and comes to treat the sluggish brain performance as normal. Maladaptation.
Unlike the acute sleep deprivation, recovery from chronic sleep deprivation will take longer. In the study reaction time performance had not recovered even three days after the sleep restriction.
One reason this chronic sleep reduction may be so detrimental to cognitive performance is that sleep, that is deep sleep, is the brain’s time to clean house. In fact this is at least one of the reasons we sleep in the first place. The human brain, with it’s souped up, turbocharged cortex, is a real energy addict. Our brains are responsible for about 20% of the energy expended at rest. All this energy use creates toxic byproducts that must be cleaned up. Byproducts such a beta amyloid proteins that are associated with Alzheimer's and memory loss. Beta amyloids have been known to increase during wakefulness and decrease during sleep. They are also associated with reduced slow wave sleep and overnight memory consolidation.
The solution is our built in brain Roomba called glymphatic circulation. It kicks into gear primarily in the deep slow wave stages of sleep. Like a free diver trying to reach record depths it takes time to get deep. It’s the same when trying to get into deep slow wave sleep. If you're chronically trading away your sack time you’ll spend less time in the deep, house cleaning stage. Here is a fascinating image of one brain that has gone through it’s beta amyloid cleaning and one that hasn’t.
Sleep has a big effect on your cognitive performance. You can bounce back from a late night here or there but, if you're gaming for better focus, memory and decision making protect yourself from the routine sleep loss that turns into a maladaptive brain.
Need help counting more sheep at night? Check out these 16 tips to get better sleep.