Russell Foster is a professor of circadian neuroscience at the University of Oxford. In this 22 minute TED talk he very helpfully explains the importance of something we so often take for granted and underestimate the importance of - sleep! Or to put it another way, sleep is the single most important behavioural experience we have. We spend on average 36% of our life sleeping. So for someone living to say the age of 90, they will have spent on average 32 years asleep! When you put it in those terms then sleep at some level is a really important part of being human. So what has science so far learnt about sleep?
Professor Foster helpfully explains that when you sleep your brain doesn't just turn off, but that there are a huge raft of different interactions going on within the brain.
So why do we sleep? Its likely that there are a multitude of different reasons. Some of the most common:
- For restoration. It has been shown within the brain there are a whole range of genes associated with restoration and metabolic pathways that are turned on only during sleep.
- For calorie conservation. While the research shows you only expend 110 calories more by not sleeping and not moving very much, this seems less likely. However, other research shows that there is more to this than just numerical calorie amounts.
- For brain processing and consolidation. In other words sleep enhances learning and creativity.
From the 1950s to the present time, average sleep times for adults in the Western world have significantly reduced. It has gond down from around 8 hours a night to around 6 1/2 hours a night. However, the craving for sleep does not go away. Instead there is the risk of micro-sleeps, or involuntary falling asleep which we have no control over. I remember an embarrassing example of that when I was a medical student rushing to an early morning lecture at a hospital. It wasn't really that early - only 8am, but I sat myself down in the front row. As I nodded off, the lecturer noticed me and said, "Am I boring you?" At that point my neighbour poked me in the ribs with his ruler causing me to jolt up and say "Yes, yes." I had no recollection of this, but was teasingly told the story after the lecture!
There are more dangerous consequences:
- 31% of drivers will fall asleep at the wheel at least once in their life.
- In the United States 100,000 accidents on the freeway have been associated with tiredness, loss of vigilance and falling asleep.
- The nuclear accident at Chernobyl and the space shuttle Challenger disaster were both after extensive investigation found to have been related to poor sleep in individuals. There was poor judgement as a consequence of extended shift work leading to a loss of vigilance and tiredness.
- Cravings for caffeine, nicotine and alcohol.
- Weight gain with a 50% increased likelihood of being obese if you sleep 5 or less hours every night. This is thought to be related to increased release of the hunger hormone, Ghrelin which causes us to seek out carbohydrates and sugar.
- Sustained stress leading to suppressed immunity and so greater infection rates as well as type two diabetes, heart disease from raised blood pressure and also higher cancer rates.
So how do you know if you are getting enough sleep? You need more sleep if:
- You need an alarm clock to get up in the morning.
- You take a long time to get up.
- You need lots of stimulants
- You are easily irritated with others
- Others tell you that you look tired and are irritable.
How do you improve your sleep habits?
- Make your bed a haven for sleep and not a place for entertainment or work. The advice is to make your bedroom as dark as you possibly can and also to make it slightly cool
- Reduce the amount of light exposure at least half an hour before going to bed. This also includes the bright light from computer and smart phone screens.
- Try not to drink caffeine too late in the day and ideally not after lunch.
- In the morning when you get up seek out bright light.
What I also found interesting from Professor Foster's talk were some so-called myths he challenged:
- Teenagers are not intrinsically lazy, but have a biological predisposition to go to bed late and get up late.
- Eight hours sleep a night is not universally applicable. It is an average and some need more while others need less. The important thing is to listen to your body and adjust accordingly.
- Older people do not need less sleep. What happens is that sleep fragments with more waking up in the night. But the need for sleep does not go down.
- Going to bed early and waking up early has not been shown from research to make you healthier, wealthier and wiser!
Also as a psychiatrist I found particularly interesting his exploration of the association between mental health, mental illness and sleep:
Mental illness and sleep are not simply associated, but they are physically linked within the brain. This comes from the discovery of the overlap of the neural networks that predispose to normal sleep with those that give normal mental health. Genes important in the generation of normal sleep when mutated also predispose to mental health problems such as schizophrenia.
Sleep disruption actually precedes certain types of mental illness, such as bipolar disorder
Sleep disruption makes worse certain mental illness states such as paranoia with research showing stabilising sleep patterns reducing levels of paranoia by as much as 50%.
To summarise, good sleep:
- Increases your concentration
- Improves attention
- Enhances decision making
- Improves creativity, social skills and general overall health.
Its getting late and I need to get some sleep!
For more on this, also see The Importance Of A Good Night's Sleep