How the secret of sleep keeps us awake

Humanity’s tormented 21st-century relationship with sleep raises a great many questions. Most can be dealt with as follows: no, not nearly enough; yes, but that would require a wholesale transformation of lifestyle and socio-economic context; OK, but that seems extortionate for a mattress. 

Yet the most basic question of the lot — how does tiredness work and what makes us sleepy? — remains tauntingly and magnificently unanswered. Cracking its secrets, says the neuroscientist who has arguably come closest to doing so, could transform the waking and sleeping world as we know it. Masashi Yanagisawa and his team have taken a bigger step towards solving the puzzle than anyone yet, but it remains (for now, at least) a flat-out mystery. Anyone who says otherwise is probably trying to sell you something.

Which, while we wait for the next scientific breakthrough, is exactly what is happening. 

Sleep is big business. Competition for our wakeful spending has fought itself into ever smaller corners of wallets and imaginations. The battle for the third of our lives that we spend asleep, meanwhile, still feels wide open to further commercial exploitation. 

Bedrooms as sanctuaries, bamboo pyjamas, sensor-laden bedding, high-end wellness tourism, sleep consultants. The industry, in all its ingenuity, has honed ever-greater skill in casting sleep as both the pathology (terrible things happen to the individual and the economy if you do not get enough) and panacea (amazing things happen if you do) of modern life. 

Judging the current scale of the sector depends on what you count, but it is arguably in the hundreds of billions of dollars. The global mattress and bedding markets are together reckoned by some to be worth over $150bn; add in bed accessories, sleep-tracking smartwatches, sleep labs, smart alarm clocks, apnoea treatment devices, sleep-related medicines, dietary supplements, sleep monitors and temperature control equipment and the figure could be approaching $300bn.

A great part of the current and projected growth of the industry derives from how comprehensively sleep, and the lack of it, are entwined in the broader discourse of health and the prevention of disease. National and supranational organisations produce surveys and recommendations on sleep, and the prevalence of smartwatches and other devices is providing an unprecedented glut of data on how well we do it. Generally, sleep seems to be clawing back the respect it has historically ceded to the demands of long working hours. 

In Yanagisawa’s home country of Japan, where he is director of the International Institute for Integrative Sleep Medicine and a powerful advocate for more and better sleep, the realisation of what happens when a nation collectively scorns its importance is hitting home.

The government’s most recent (pre-Covid) figures found roughly 40 per cent of adult men and women in the country got less than six hours of sleep a night. A 2021 OECD survey found that Japanese people get, on average, the least among the 33 nations polled. The Pokemon Sleep app, now downloaded by 10mn people around the world, confirmed those findings.

By the time they are in high school, about a third of Japan’s children, a University of Tokyo study revealed last month, are getting less than six hours a night and falling victim to “social jet lag”.

In this situation, Yanagisawa finds himself with two roles. As one of the world’s great sleep scientists, he is a natural and charismatic proselytiser. But, in the long run, his work could make a practical difference.

Its focus is on the mechanism in the brain that controls the quality and quantity of sleep — the heart of the mystery about what happens during waking hours that later builds to sleepiness. For something so fundamental, he says, it is far more complex than people imagine. Scientists are broadly agreed on the concept of a switch that flips a person between the states of wake and sleep. The puzzle is how it works and how the brain “counts” the accumulation of sleepiness.

In 2021, a team from Yanagisawa’s institute discovered that an enzyme called salt-inducible kinase 3 could be central to how sleep is regulated — and is possibly the clue everyone has been looking for.

Yanagisawa, sitting in his modest office in Tsukuba, is measured but excited. If science can work out how our sleep switch works, and what controls how long and well we sleep, the practical consequences could be vast.

“We will be able to start manipulating this mechanism. You could develop an entirely new class of medicine that, when necessary keeps you awake, or when necessary gives you all the hours sleep you need,” he says. Miseries like sleep deprivation and insomnia could, overnight, become things of the past. 

The sleep industry might be on track for its biggest revolution since the pillow.

leo.lewis@ft.com