The science of sleep
Posted on 18 December 2017
Three American doctors were awarded the 2017 Nobel Prize in physiology or medicine for recent discoveries about sleep. Jeffrey C. Hall, Michael Rosbash and Michael W. Young have spent years researching the body’s circadian responses to light and dark. A neurologist practising at Mediclinic comments.
The doctors were awarded the honour in October, when the prize committee praised the scientists for explaining how an “inner clock” can adapt and fluctuate to optimise a person or animal’s behaviour. ‘Their discoveries explain how plants, animals and humans adapt their biological rhythm so that it is synchronised with the Earth’s revolutions,’ said the committee.
Because the circadian system involves almost every tissue in the body, according to Dr Rosbash, this research is an important breakthrough in how doctors understand the effects of sleep on several conditions and disorders – even jetlag.
There’s a lot going on behind closed eyes
Whereas doctors once considered sleep to be passive rest and recuperation, we now know it is a very active process, says Dr Kevin Rosman who runs the Sleep Clinic at Mediclinic Morningside.
‘If you look at the electrical activity in the brain while we sleep, in some ways, and at some stages, it may be even more active than during our waking hours,’ he explains. ‘During sleep we consolidate memory and dispense with unnecessary memories. Sleep also controls numerous body functions including your hormones, bone growth, mood, memory, immunity, tissue repair, and more.’
Sleep is critical – at all stages of life
Your need for quality sleep doesn’t change much as you age, but how much you need will fluctuate as you grow. ‘Children and adults require sleep essentially for the same reasons, but because a child’s brain is growing very actively, more sleep is needed,’ says Dr Rosman. ‘An infant may require 20 hours a day, while the average for a young adult is about 7 1/2 hours a day. This becomes less as we get older.’
You don’t function normally when you’re deprived of sleep, says Dr Rosman, and that’s why you crave it so much. ‘Think about it this way: all the good stuff in our brains happens while we sleep, and the bad stuff happens during the day.’
This is why going without sleep can be hazardous for your health. ‘Driving after being awake for 19 hours is as dangerous as driving over the legal limit for alcohol. And driving after being awake for 26 hours is as dangerous as driving at double the legal limit of alcohol.’
Your sleep patterns may be genetic
When you sleep, your body uses that downtime to secrete toxins. ‘Sleep occurs in cycles of approximately 90 minutes,’ Dr Rosman explains. ‘Level one is drowsiness, level two is light sleep, level three is deep sleep, otherwise called slow-wave sleep (because of the way the EEG looks in the stage of sleep), and the last stage is called REM sleep (rapid eye movement).’
This may give the impression that good sleep is a formula, and you’d be better off following 90-minute cycles. But, as Dr Rosman explains, the exact amount of sleep you need is genetically determined and differs from person to person.
Go towards the light
Scientists have seen for centuries how plants and animals change their behaviours in sync with the light in their natural environment. Hall, Rosbash and Young have now determined exactly how this happens.
Dr Rosman explains: ‘when you are exposed to bright light in the morning, this suppresses your body’s production of melatonin. When the light dims towards the end of the day, melatonin production increases. This is what puts you to sleep a few hours later.’
What happens if your sleep is out of sync?
Your body’s physiological processes run on their own cycles. The light-dark cycle plays a crucial role in realigning these patterns, says Dr Rosman. Interrupted or irregular sleep can lead to incorrect alignment, known as jetlag.
The award-winning scientists’ work has major implications for medicine, as misaligned circadian rhythms have been linked to the onset of Alzheimer’s, depression, worsened attention-deficit/hyperactivity disorder (ADHD) symptoms, heart disease, obesity and diabetes as well as other metabolic issues.
How do we ensure we sleep better?
Quality rest is all about what Dr Rosman calls “sleep hygiene” – the process of getting ready for bed:
- Go to bed and get up at the same time every day;
- Wind down before getting into bed;
- Invest in a comfortable bed and mattress; and
- Make sure your bedroom is quiet, dark, cool and secure.
But most importantly, know the consequences
Dr Rosman stresses that the most important step towards ensuring you sleep better is understanding what can happen if you don’t. ‘There are over 80 different sleep disorders. These are just as much a risk to your health as heart failure. Bad sleep can actually worsen your blood sugar levels, and certain sleep disorders can increase your risk of heart attack.’