How important is sleep? It’s crucial for life. In lab studies, rats deprived of sleep can’t stay alive for more than a month. This holds true for humans as well. People with a rare condition called fatal familial insomnia die within 18 months because they can’t fall asleep. These unfortunate folks lose nerve cells in a region of the brain called the thalamus that consolidates sensory information. This devastating disease is caused by an inherited misfolded protein called a prion.
Fortunately, most of us don’t have to deal with being completely unable to sleep, although we DO have to worry about getting enough sleep. One reason you need it is for overall health. Sleep serves a useful purpose – it helps cells and tissues repair. One organ in particular, is impacted by not enough sleep – your brain. When you don’t sleep enough for a night or two, you feel the effects in your brain – your thinking slows and you don’t feel motivated. Why is sleep so vital for the brain?
Sleep Allows Your Brain to “Clean Up”
Throughout the day, your brain accumulates waste and toxins. If they aren’t cleared, they build up in the tissues in your brain. Fortunately, your brain has special channels called the “glymphatics,” a sort of auxiliary lymphatic system, which drains toxins and damaged proteins. When this clearing takes place is at night while you’re sleeping. In people with Alzheimer’s disease, you see a build-up of B-amyloid protein. Research suggests that inadequate clearance of damaged proteins plays a role in the brain changes you see with this common form of dementia. These proteins often build up years before frank symptoms of Alzheimer’s develop.
Interestingly, your sleep position may be a factor in how well you clear damaged protein and toxins. A study showed that when rats slept on their side, the glymphatics of the animals better cleared toxins and waste from the brain. Researchers believe that the same may apply to humans as well. So, sleeping on your side and getting enough quality sleep are steps you can take to help your brain clean up and “detoxify.”
It’s during sleep that the new insights you gain and the things you learn during the day are solidified and transferred to longer term storage. For example, research shows if you study for a test and sleep for a certain number of hours, you’ll likely recall more than if you wait the same number of hours without sleeping before retesting. Sleep is helpful for making memories stables, so you can bring them to mind at a future time.
For something that you learn to stick in your head you first have to acquire the information. This happens during waking hours. But once acquired, the information will be fleeting unless it’s transferred and consolidated into long-term memory storage. That’s what happens when you sleep – memory consolidation takes place. Once consolidated, it’s more likely that you can access or recall the information when you need it. Consolidation is the “in between” step between learning something and being able to recall it.
It’s also during sleep that your brain weeds through and discards irrelevant connections and information that’s not important to hang on to. Without this weeding process, old information would clog your brain and make it more difficult to learn new things and form new memories. So, sleep is a type of housecleaning for the brain – a chance to eliminate clutter, much like you clean up your home or office. This “clean sweep” happens at night while you sleep.
Creativity May Suffer When You Don’t Sleep Enough
Sleep is most constructive to the ability to think divergently or think “out of the box.” Small studies show that convergent thinking, the ability to think in straightforward, logical ways is not greatly affected by skimping on sleep unless the loss of sleep is extreme. However, you’re less likely to come up with a creative solution to a problem when you’re not getting enough shuteye.
Yet, not every study supports this idea. Some research suggests that skimping a little on sleep may actually enhance creativity. You’ve probably heard of people who grabbed a notepad and wrote a song or penned the solution to a problem when they were unable to sleep. One theory is that when you’re sleepy from lack of sleep, your mind taps into deeper states of consciousness, similar to what you access when you DO sleep, and can make new associations. Regardless of whether sleep suppresses creativity or enhances it, it’s not healthy or productive to skimp on sleep too often.
Sleep is a Mood Stabilizer
Lack of quality sleep can impact another aspect of brain function – your mental health. Sleep has a restorative function on the portions of your brain involved in mental wellbeing. Studies show that not getting quality sleep can bring on or worsen feelings of depression. Some people even experience auditory or visual hallucinations when deprived of sleep for more than a night or two.
It’s not just lack of sleep but frequent awakenings and interruptions during the night that can negatively impact your mood. Researchers at Johns Hopkins found that interrupted sleep was more detrimental to mood than not getting enough sleep. Plus, they found the effects are cumulative. Several nights in a row of interrupted sleep affect mood more profoundly than a single night. So, sleep quality matters as much as how long you sleep.
The Bottom Line
Now you know why sleep is important for brain health – but it’s vital for the functioning of all of your systems from your immune system to your heart. So, make sure you’re getting enough sleep and that it’s uninterrupted. Next to food and water, it’s the most important thing your body needs.
Nat Rev Neurol. 2015 Aug; 11(8): 457–470. Published online 2015 Jul 21. doi: 10.1038/nrneurol.2015.119.
Johns Hopkins Medicine. “Sleep Interruptions Worse for Mood Than Overall Reduced Amount of Sleep, Study Finds”
Science Alert. “Sleeping on Your Side Could Reduce Alzheimer’s And Parkinson’s Risk, Study Finds”Journal of Neuroscience 5 August 2015, 35 (31) 11034-11044; DOI: https://doi.org/10.1523/JNEUROSCI.1625-15.2015.
Forbes.com. “7 Ways Sleep Affects The Brain (And What Happens If It Doesn’t Get Enough”
Scientific American. “Beyond Memory: The Benefits of Sleep”
StayingSharp.com. “Sleep’s Connection to Creativity Not Just Something You Dreamed Up”