You know that feeling when you just woke up, but it feels like you slept only for five minutes? Yeah, I do too. That’s your body letting you know that you are sleep deprived. If you think about it, you can picture yourself being essentially a zombie the rest of that day. Or if you’re like me, you’ll have massive amounts of energy but yet still manage to be completely unproductive. Don’t those days feel like a blur? Like, ‘it was a good day but I can’t really remember what happened’?
Sleep deprivation is shortened sleep that can come about as a result of a number of factors. You might have insomnia (which affects 1 in 3 people) and find it hard to fall asleep, or wake up earlier than you intend and not fall back asleep. You could have sleep fragmentation where you sleep for the recommended 7-9 hours but constantly wake up during the night. Of course, because we enjoy extreme sports, we also choose to restrict our sleep for school, work or recreational purposes. No matter the reason for your sleep deprivation, the consequences are still severe and we’ll start by looking at consequences in learning and memory.
So first, crash course. There are four main stages of sleep (N1, N2, deep sleep and REM), each playing a different role. N1 is the first stage, basically, the stage where you feel like you’re falling into an abyss and keep waking up to check on your body parts. N2 is when you have fallen deeper, this is often where the drooling starts. Deep sleep (also called slow-wave sleep) is the deepest stage. You know when people say they called you a hundred times, but you never heard a thing, you were in deep sleep. Lastly, we have REM (rapid eye movement) which is the sleepwalking, sleep talking, night terrors and vivid dreams stage of the night. N2, deep sleep and REM cycle every 90 minutes during the sleep period.
Coincidentally, N2, deep sleep and REM are the stages important for retaining and consolidating procedural and declarative memory. Declarative memory refers to information recall from previous learning episodes (like remembering your multiplication table), and procedural memory refers to behavioural, learned tasks such as riding a bike or driving a car, and. So we’ll just call them ‘know stuff (declarative)’ and ‘do stuff (procedural)’. N2 sleep has been linked to improving recall of ‘know stuff’ memory. A study done on participants who were taught word-pairs showed that increased N2 resulted in higher scores and faster times when remembering the information. Similarly, we see a substantial increase in REM sleep following days of learning a lot of information; deprivation of REM results in an inability to recall learned information. For example, a study where participants were taught number series before going to sleep episode found that those who didn’t get enough REM took longer to remember what they learned. Lastly, deprivation of just the deep sleep decreases your chances of storing long-term ‘do stuff’ memory.
So, why did I just tell you all of this mumbo jumbo? Based on this wisdom I’m dropping right now, you can imagine what sleeping only a fraction of the recommended time can do to your memory consolidation from things learned previously, as well as your ability to learn and concentrate on the new day you’re starting. Essentially, if I don’t get myself in bed within the next fifteen minutes, I will only get 6 (or less) hours of sleep tonight. As a result, I will need to heavily revise for my NATO exam coming up because I won’t get enough N2 and REM to effectively remember all the things I learned today. Spending time and effort studying is great and important, but your brain needs time to store that new information to long-term memory, and that time is sleep.
I know you are wondering, why can’t I sleep only 4 hours and still get the same benefits? Well, deep sleep is more concentrated during the first 4 hours of sleep, and REM is more concentrated during the last half. So, what I’m saying is if you sleep only half the night you will either get declarative but not procedural memory consolidation, or vice versa.
The moral of the story is… Go to sleep. Sleep well and long, and don’t let anyone wake you up to wash the dishes.