We’ve forgotten how to sleep and it’s affecting our mental health, says the head of the world’s first institute devoted to the neuroscience of this most basic activity.
By Linda Loder
‘Sleep is the single most important behavioural experience that we have’ (Russell Foster, Professor of Circadian Neuroscience and Director of the Sleep and Circadian Neuroscience Institute, Oxford University)
As a boy, Professor Russell Foster loved looking through his microscope but his eyelashes kept getting in the way — so he cut them off. At Bristol University, he suggested that the human eye might have a mechanism similar to the ‘third eye’ of some vertebrates, which registers natural light levels and is linked with the body clock. Ophthalmologists were testy: did he really think there could be anything they had missed during 150 years of research? He replied that he did and they had. He was right.
A breakthrough came during an experiment in which subjects identified when a light was turned on or off. A completely blind patient humoured the scientists and had a go. Astoundingly, she was able to identify accurately the presence of a light she could not consciously see at all.
Just as the ear is connected both with hearing and balance, it became clear that while the eye contains rod and cone cells that give us a picture of the world around us, it also has photoreceptors that detect environmental brightness. These cells plug into the parts of the brain that regulate the body clock — our internal, circadian rhythm that tells us when to sleep and wake.
In our 24/7, wired society we have light to drive away the darkness, and light-emitting electronic gadgets to entertain us on demand. We work through the night and travel between time zones. We may have dispensed with candles, but are we still metaphorically burning them at both ends? ‘After four billion years of evolution, we are extraordinarily arrogant in that we think we can simply override our internal biology,’ says Professor Foster.
Furthermore, we often have unrealistic expectations of sleep. Waking up in the night is actually a normal part of human physiology; our natural cycle includes a short period of wakefulness between two longer periods of sleep. There is plenty of historical evidence that in pre-industrial times people had two ‘sleeps’, starting at dusk, with a waking period in between during which they might remain in bed but perhaps read, write or pray.
Humans have varying sleep requirements, as well as their own chronotypes. Are you an ‘owl’ or a ‘lark’ — or neither? Professor Foster jokes that we could chronotype the population so that people could fit their employment to suit. Imagine city workers allocated to the global financial markets which best suited their sleep/wake cycles.
Contrary to what has always been thought, the bodies of shift workers never adapt to working at night. Their biology is wired into exactly the same light/dark cycle as a day worker’s, and overriding that internal clock over many years has been associated with higher risks of cancer, cardiovascular disease and type 2 diabetes. Professor Foster points out: ‘Over 30 per cent of the medical problems that doctors are faced with stem directly or indirectly from sleep. But sleep has been ignored in medical training and there are very few centres where sleep is studied.’
Thanks to a grant from the Sir Jules Thorn Charitable Trust, it will now be possible to create a physical home for the Sleep and Circadian Neuroscience Institute, directed by Professor Foster. It already exists in virtual form but the new plans are based around researchers and clinicians interacting daily on one site — and they include public space for engaging with patient groups and other non-specialists.
Severe sleep and circadian rhythm disruption (SCRD), according to the institute, is a feature shared by some of the most challenging diseases of our time — from schizophrenia and bipolar disorder to Alzheimer’s disease and stroke. An important part of the institute’s work will be to investigate the neural networks involved in normal sleep and those that predispose us to normal mental health — mechanisms which appear to overlap. Scientists are now showing that improving a patient’s sleep can alleviate some mental problems. As Professor Foster says, ‘We can identify the sleep centres of the brain as a new therapeutic target, offering the opportunity to reduce some of the appalling symptoms of mental illness.’
For the rest of us, tired brains crave stimulants — alcohol, caffeine, nicotine — which can lead to further health problems. While a glass of wine might occasionally help ease the transition into sleep, it is essentially a sedative. Professor Foster warns that it will therefore inhibit vital brain processes that go on during sleep, such as consolidating memory and improving our ability to learn tasks and solve complex problems. So it’s not one for the long term. Good sleep has been likened to an upgrade from economy to business class — but without sleep, according to Professor Foster, we don’t even get on the plane.
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Main image: ‘It’s Time to Sleep’ by Rachel Calamusa via Flickr under Creative Commons licence. Sleep graphic by One Ltd and photo of Professor Russell Foster by John Cairns both reproduced with permission.