Sleeping is an innate behaviour, it’s genetically programmed and anchored that all animals need sleep. And there’s going to be individual differences, cultural differences, political and economical factors that are going to influence people’s habit of sleeping. So, you have giraffes – they sleep two hours a night. And then you have cats, lions, and they’re going to sleep 20 hours a day. And humans, we’re kind of in the middle of the animal range, around 8.2 hours on average. That’s what has been observed usually.
This average of 8.2 hours of sleep, it’s going to vary between individuals, but it’s also going to vary within individuals, in the course of their lifetime. So, for example, newborn babies. When you’re a baby, the brain is not completely developed, like adult form. So we know that the sleep cycles, the REM and NREM don’t exist yet. Which is why babies wake up in the night and it’s quite disruptive, difficult to predict, etc.
But they’re still going to sleep quite a lot. It won’t be an eight hour point two average, it’s going to be, maybe, a lot more than that. And then kids, they start to get into a night and day schedule of sleep, and follow what the society has created as the sleep pattern that we want for them. So, daytime awake, night-time sleeping.
When you become a teenager, it’s the phase where the brain is going to change again, so much, through the process of that phase in sleep. Synapses are going to change, meaning that information they’ve learnt that is valuable is going to be reinforced during sleep. And information that they don’t need, or synapses in the brain that they don’t need are going to start to disappear. And all this happens during sleep.
So teenagers are going to start to sleep quite a lot again. And for biological reasons too, they’re going to go to bed later. So, usually we see two hours delay compared to when they were kids. And it’s quite interesting, because, at The Kusnacht Practice, we treat mental health and we see that, in teenagers, they’re kind of constantly in this social jet lag because they still have to wake up at 8 a.m. to go to school. Even though the brain is in reconstruction, and technically, they’d need more sleep, and sleep that’s following a different schedule.
And then, when you’re an adult, you’re going to get into a sleep routine that’s usually stable until you become a senior. At that age, we observe again, that sleep becomes fragmented, less deep, and that people sleep less. We don’t really know why, the most likely hypothesis is that it’s due to medication intake, which is quite common at that age.
So, how we sleep varies within a person, in the course of their lifetime. It’s going to vary from one individual to another, where we each have a different baseline around 8.2 hours, but there’s going to be some variability there. Sleep is important. Indispensable actually. It’s a vital need for a lot of different reasons.
When someone is diverting away from what their own baseline is, again, usually the average is 8.2 hours, what’s interesting is that we see a huge difference between the impact it has on them objectively, that we can measure and that has been observed in labs, and what they report subjectively. So, if it happens for a few nights, where someone’s not sleeping so well, humans have resources, so they’ll manage to compensate.
But, if it becomes more chronic, over time, it’s going to create problems on lots of different psychological and physical factors. So they might start having difficulty with concentration, emotion regulation, memory, creativity, problem solving, and lots of other factors. But subjectively, they’re going to have a tendency to think that they can still perform at the same level.
There’s been some studies that were done. One I can think of was with individuals that were deprived of different amounts of sleep in a night. So, maybe, it was eight hours of sleep, then four, then two, etc. I don’t know the exact numbers. And then, the next day, they had to drive a car. And they measured the reaction time that it took them to respond to a sudden need to brake, to stop the car. They realised that everybody, when they had to evaluate their performance, they all said they did amazing. They were fine, they were awake, all good, regardless of how much they slept.
But, objectively, we saw very important differences in the reaction time. So there is this objective versus subjective component. And then, physically, we also know that once someone can no longer compensate, after the first few days or weeks, etc, for the lack of sleep, we’re going to see an increase in the risk of cardiovascular diseases. We’re going to see impacts on the brain, hormonal regulation, and a lot of different factors.