Sleep is so abused these days. In 1910, the average American slept 9 hours a night. Now we average 7.6 hours a night and falling. There is just so much more fun to be had awake – or a bit more money to be made working on the ‘net with others in different time zones.
As the clip says, we pay a heavy price.
Ideally we start the day with high cortisol levels – one of the stress hormones. This enables us to cope with life ahead. As the day goes on, cortisol starts to drop and melatonin starts to rise, so in the evening we get sleepy and go to bed. We sleep deeply for the 7 – 9 hours that we need, then wake refreshed without needing an alarm clock.
That is ideal. When we are not stressed. Hey, this may happen on a good holiday! But when we are in our usual mouse on a wheel battle through life, stress is high and you have to be very vigilant to make it drop properly to get a good night’s sleep. Don’t watch telly or be on the computer straight before bed. Do nice relaxing things instead – bath, read a book, listen to calming music etc.
If you are stressed when you go to sleep, slow wave sleep is decreased – the deep restful sleep. The brain is just too full of cortisol to let itself rest properly. It spends the night dreaming. So the quality of your sleep suffers and you wake tired. To quote the old joke ‘The lion and the lamb shall lie down together. But the lamb won’t get much sleep’.
In his book ‘Why Zebras Don’t Get Ulcers’, Robert Sapolsky describes an experiment conducted on a well rested subject and a tired subject. Both were put into a brain imager and asked to solve some “working memory” problems (remembering some facts then manipulating them, eg adding sequences of 3-digit numbers). As the well rested subject did the tasks, the frontal cortex of the brain lit up. 1 When the tired subject did the tasks to everybody’s surprise, not only did the frontal cortex light up, but so did large parts of the rest of the cortex. “It’s as if sleep deprivation has reduced this gleaming computer of a frontal cortex to a bunch of unshaven gibbering neurons counting on their toes, having to ask the rest of their cortical buddies to help out with this tough math problem.”
So not getting enough sleep makes you stupid as well as fat, cross and clumsy.
- Our brain has developed over the millenia and the frontal cortex is the most recent development of all. Essentially it is The Captain of the brain and responsible for problem solving, motor control, empathy, reasoning and memory. Parents of teenagers will have an Aha moment when told that this is the last part of the brain to develop. [↩]