Many theories have been put forward over the years to explain why we need to sleep, how much is the right amount, and the fundamental purpose of slumber. You can help scientists to explore the mystery of sleep by taking part in a huge online experiment, on worldslargestsleepstudy.com.
The experiment uses an approach that I helped to develop for a mass participation study of intelligence with Adrian Owen and his team from the University of Western Ontario, when 110,000 people took part and the results were published in the journal Neuron.
For the sleep study, which he briefly discussed with me at a recent Lates in the Science Museum, participants will undergo a series of intelligence tests designed to trigger activity in as much of the brain’s anatomy as possible, combining the fewest tasks to cover the broadest range of cognitive skills.
Every participant will be asked to complete the tests before going to bed at night, as well as completing a questionnaire about lifestyle and personal details
They will then be asked to complete the tests again when they wake up, and provide details about when they went to bed, when they woke up and what sort of night’s sleep they got.
If you take part, you will learn how long you slept relative to the rest of the population, whether you retired to bed earlier or later than others and so on, as well as insights into your cognitive performance.
And you will be invited to have a second go, after a night that was as different as possible as the one you had the first time around.
The issue is important, says Owen, because many professions encourage or require frequent sleep deprivation, notably in healthcare, transport and law enforcement. Productivity lost due to sleepy brains costs countries billions – one 2016 study concluded the impact was an estimated $50 billion in the UK alone.
At the level of an individual, being awake for 18 hours had an effect on cognition equivalent to being mildly intoxicated, said Owen.
But there is still a lot to learn, he says: which groups of people are most susceptible to the effects of sleep deprivation? Does the effect of sleep on cognition change with age?
We know that elderly people require less sleep, but does that interfere with their cognitive performance? Does the time you go to sleep matter – or is the secret just to make sure you get enough hours in?
And finally, we all know that getting a good night’s sleep is important for brain health, but how much sleep is enough?
A pilot study by Owen of around 500 people already shows that less sleep harms reasoning and memory, while verbal skills are less impaired, suggesting that those brain systems that are responsible for high-level decision making, planning and problem solving may be disproportionately affected by not having enough sleep – including, paradoxically, the ability to detect that deprivation has made your performance below par.
Owen will also discuss his sleep experiment with me later this year at the Manchester Science Festival.