Sleep science has entered a golden age of discovery. Researchers now understand sleep’s role in memory consolidation, immune function, Alzheimer’s risk, cardiovascular health, and emotional regulation at a level that would have seemed implausible twenty years ago. So why is the public, and policy, still treating sleep as optional?
The discovery nobody is taking seriously enough
In 2013, Maiken Nedergaard and her colleagues at the University of Rochester published a paper in Science that should have remade the cultural conversation about sleep. They discovered that during sleep, the brain’s glymphatic system, a network of channels through which cerebrospinal fluid flows, dramatically increases its activity, flushing out metabolic waste products including beta-amyloid and tau proteins: the same proteins that accumulate in the brains of Alzheimer’s patients.
Sleep, in other words, is when the brain takes out its own rubbish. And if the rubbish is not collected regularly enough, the evidence suggests it accumulates. A 2021 study in Nature Communications, tracking over 7,000 UK participants over 25 years, found that consistently sleeping six hours or less per night in midlife was associated with a 30 per cent increased risk of developing dementia, independent of other health and behavioural risk factors.
Professor Matthew Walker, director of the Centre for Human Sleep Science at UC Berkeley and author of Why We Sleep, has described insufficient sleep as ‘one of the greatest public health challenges we face in the 21st century.’ He is not alone in that assessment. The question is why it has generated so little policy response.
How much sleep do we actually need
The scientific consensus, as reflected in recommendations from the American Academy of Sleep Medicine, the National Sleep Foundation, and the NHS, is that adults require between seven and nine hours of sleep per night for optimal health. Children and teenagers require substantially more. Yet data from the 2022 UK Sleep Survey, conducted by the Sleep Charity, found that 36 per cent of UK adults sleep fewer than six hours on weekdays, and 67 per cent report their sleep quality as poor.
These are not abstract numbers. Cognitive performance after 17 hours of wakefulness, roughly a standard day for many adults, is equivalent to a blood alcohol concentration of 0.05 per cent. After 24 hours without sleep, it reaches the equivalent of 0.10 per cent: legally drunk in most jurisdictions. Yet we do not regulate sleep deprivation in the same way we regulate alcohol, in almost any professional or legal context.
‘Sleep is the single most effective thing we can do to reset our brain and body health each day. Yet it is the one behaviour we are most ready to sacrifice.’
The immune dimension
The connection between sleep and immune function has been understood in broad terms for decades, but recent research has made it far more precise. A landmark study published in the Journal of Experimental Medicine in 2019 found that sleep dramatically enhances the adhesion properties of T cells, key players in the immune response, through mechanisms involving specific hormones released only during sleep. The implication is direct: insufficient sleep reduces not just the quantity but the effectiveness of immune cells.
A famous Carnegie Mellon study, in which participants were deliberately exposed to rhinovirus (the common cold) after their sleep duration was documented, found that those sleeping fewer than six hours per night were 4.2 times more likely to catch a cold than those sleeping seven hours or more. Vaccine efficacy research tells a similar story: individuals who slept fewer than six hours in the week before receiving a hepatitis B vaccine generated less than half the antibody response of those sleeping eight hours or more.
Sleep and mental health: a bidirectional relationship
The relationship between sleep and mental health is among the most robust in the psychiatric literature, and among the most frequently misunderstood. Poor sleep is a risk factor for depression and anxiety; depression and anxiety disrupt sleep; and the resulting cycle is one of the most common drivers of clinical deterioration in people with mental health conditions. Sleep disturbance is now recognised as a transdiagnostic factor, present across almost all psychiatric diagnoses, and is increasingly being targeted as a primary intervention rather than merely a symptom.
Cognitive behavioural therapy for insomnia (CBT-I), a structured programme that addresses the thoughts and behaviours that perpetuate sleep problems, has the strongest evidence base of any treatment for chronic insomnia, outperforming sleep medication on every long-term outcome measure and without the dependency risks associated with benzodiazepines and Z-drugs. Yet it remains difficult to access on the NHS, and many GPs continue to reach for a prescription rather than a referral.
Why the culture resists
Cultural attitudes toward sleep deprivation are stubbornly resistant to change, particularly in professional contexts where busyness and early rising are worn as badges of identity and productivity. Silicon Valley’s ‘I’ll sleep when I’m dead’ culture (a phrase that, in light of the dementia data, reads less like ambition than prophecy) has influenced workplace cultures globally. The idea that sleep can be sacrificed without consequence has been economically convenient for employers and productivity ideologies alike.
Recent shifts are detectable, but slow. The explosion of interest in sleep tracking through wearable devices has made sleep data personally visible in a way it never previously was, though research suggests that excessive focus on sleep tracking can itself generate anxiety (a phenomenon now termed ‘orthosomnia’). Several major corporations, including Google and Nike, have introduced napping facilities. A handful of countries are debating legal protections for sleep as a workplace health issue.
What has not happened is the kind of sustained, well-funded public health campaign that has accompanied smoking cessation, physical activity, and dietary change. Sleep has no lobby. It is not commercially interesting. And until the science of what sleep deprivation costs us (in healthcare, in productivity, in cognitive decline, in years of healthy life) is made visible and urgent, it is unlikely to get the political attention it deserves.