The Re:Generative Power of Sleep

I would like to share with you the talk Regenerative Power of Sleep given by Russell Foster and Till Roenneberg at the Cheltenham Science Festival 2013.

As this talk was later in the evening we were a bit worried that we might actually fall asleep but we didn't need to be as it was very exciting. Russell spoke first, initially outlining the different areas of the brain involved in sleep. One of them, suprachiasmatic nucleus (SCN),Is what gives rise to a 24-hour cycle. All the different areas and their neurotransmitters feed forward into the cortex to keep us awake. The ventrolateral preoptic nucleus (VLPO) is the sleep switch, which when activated starts the sleep cycle by inhibiting the waking systems.

Because so many brain areas involved, it means that it is highly vulnerable to disruption which can lead to health problems. This is not just mental health problems but sleep deprived people are more likely to put on weight as well. Sleep affects different systems in the body in different ways.

When sleep is disrupted we are more likely to need caffeine (and cigarettes) to wake up in the morning, but coffee interferes with the receptors for the VLPO which helps keep us awake, but then we need to get to sleep so turn to alcohol and sedatives which leads to the wrong kind of sleep which leads to more sleep deprivation which leads to more coffee so we get into a downward spiral.

Russell presented a long list of problems caused by sleep deprivation and they are the same ones as in mental health disorders. This has been known about since the 1880s, but has been ignored. In the 1970s it was thought that sleep deprivation was the by product of antipsychotic drugs so people assumed it was 'normal' and didn't bother with it.

Research has shown that mental illness and sleep deprivation are very commonly found together and lead to poor health, and that sleep deprivation precedes the illness and appears to be a feature of risk for the development of mental illness. With schizophrenia it appears that they have no clock or melatonin routines. Research from Dan Freeman has shown that intervention to improve sleep patterns leads to reduced symptoms or can delay the onset of illness

Russell then handed over to Till to speak about social jet lag. Sleep to disruption has become normal in the modern world during workdays as sleep is defined by our bosses. They have done a huge survey to find out people's chronotype, that is whether they are larks or owls, but mostly people are in the middle.

Our body clocks are not set by social circumstances, it is set by the brain and depends on the age and genes. At puberty young people go to sleep later and later and then they suddenly go onto an adult clock at age 19 1⁄2 for females and 21 in males. The chronotype doesn't dictate how many hours someone sleeps so duration is independent of chronotype, and duration is challenged by social pressures during workdays.

So owls who would normally sleep later have to sleep more on the weekends to catch up which results in a type of jet lag. As they are later to sleep at night but later to wake in the morning for just 2 days, their body clock never gets a chance to adjust to it. Teens suffer the most is their sleep cycle is later than adults but they still have to get up for school. This sleep discrepancy results in the strongest social jet lag. T his could account for the increase in drinking and smoking and young people. There is also relationship between social jet lag and weight gain. Oh, and larks have a similar problem only involving the other end of the day.

Till then went on to discuss the difference between Germans and the British. They did some large-scale studies controlling for age and sex with 75,000 Germans and so far 5,000 British. You can take the survey here. They found that we have an identical distribution of chronotypes, spent the same amount of time outside, have similar sleep duration, with the UK sleeping 8.5 more minutes a day which results in 40 extra minutes a week.

But the UK has less social jet lag because Germans go into work early! This could be because there are more factory jobs in Germany.

At the end several members of the audience had questions. One ask Till to define senile bed flight. It does sound rather worrying but he made it sound quite fun. Older people need less sleep and can get by with a little nap in the day when needed. Evolutionarily this was well suited to grandparents matching the sleep patterns of the babies so that they could take care of the babies at night and early morning while the teen parents got some sleep. So it is a very positive thing to have when looking after grandchildren!

There was a question about the effects of continuous daylight. Constant light means that there is no local body clock. The body clock drifts later and later which results in an internal body systems becoming unsynchronised with brain, gut and muscles all adrift.

I felt that this could have an implication for those with SEN and disabled children who have sleep disturbances. Sleep affects all systems. Some people believe the digestive problems on what causes autism in some children. But perhaps it is disruptive sleep and sleep deprivation which is causing both cognitive and the digestive problems. More research needed no doubt!

Russell explained that alcohol and sedatives don't work, you need to make sure that you are exposed to light, especially in the morning, and you need to listen to your body. If you need an alarm clock you are not getting enough sleep. So with teens, let them sleep in the mornings so that they don't get sleep deprived, but make sure that the curtains are opened so that they will get light through their eyelids and their brains will know it is daytime. They found that in schools, starting classes later resulted in an increase in exam results, a decrease in truancy, depression and self harm, and an increase in sleep and better eating habits.

So, far from falling asleep, we were wide awake for the entirety of the talk, and even afterwards when Till and Russell kindly signed their books for us and gave Ram a little pep talk about not being on the computer too late into the evening! For his part, Ram suggested that maybe Russell shouldn't be drinking that glass of wine either!