CIRCADIAN SOLUTIONS

Turns out we’ve been looking for ZZZs in all the wrong places. What we need is to support our circadian rhythms

Restorative sleep has never been more important – or more elusive, as anxiety around Covid-19 has us tossing and turning. But have we been searching for ZZZs in all the wrong places? Forget milky drinks and weighted blankets – research now suggests what we need most is to support our circadian health.

‘ Circadian rhythms’ might sound like an ’80s synth-pop band, but they’re key to our biology and our health. They’re the physical, mental and behavioural changes all organisms, including humans, have evolved to respond to – our internal body clocks controlling virtually every biological system, from our sleeping and waking cycles to mood and performance levels, and metabolic, reproductive and immune systems. And those immune systems have never been more important than in the war on Covid-19.

To keep our immunity strong and be in the best physical and mental shape to fight infection, most of us need seven to eight hours of sleep a night. ‘A few people can get by with five hours and wake feeling refreshed, which is what counts,’ says Michelle Baker, a Durbanbased clinical psychologist with a special interest in sleep. But regularly getting less than five hours has been linked to a raft of ills, from increased inflammation, high blood pressure and insulin resistance to weight gain, cardiovascular disease, impaired blood sugar regulation and the big one right now – impaired immunity.

The impact of poor sleep on immunity has been shown in several studies, such as one done last year at the University of California, which found that people who got less than six hours of sleep a night were four times more at risk of catching a cold when exposed to the virus than those who had seven hours or more. ‘Another study showed an increased risk of catching pneumonia with less than five hours of sleep,’ says Dr Alison Bentley, who runs a sleep therapy clinic at the Wits University Donald Gordon Medical Centre.

The reason comes down to our T cells – white blood cells that ward off infection by attacking and destroying virus-carrying cells before they can multiply. Sleep boosts our production of T cells; getting too little sleep weakens it. Crucial too is our production of proteins called cytokines, secreted by certain cells of the immune system, that help the immune system respond fast to foreign substances. ‘Cytokines direct cells to head towards infections to fight them, and the brain disposes of waste during sleep,’ Baker says.

You need a proper night’s sleep to replenish these cells and proteins, and ward off a disease like Covid-19. But many of us are struggling to get our ZZZs because of stress about coronavirus, job security, the economy, the political implications and the uncertain future.

But for a growing number of sleep researchers, one of the biggest reasons lies in something few of us may have considered: defying our circadian biology. ‘It can be difficult to adjust to a new daily schedule or lack of schedule in lockdown,’ notes the US National Sleep Foundation – and the same applies to the new work-from-home ‘normal’ replacing it. Keeping track of the time, and even the day, can be tricky without markers such as arriving at the office, attending regular social events or going to the gym, the foundation says. And here’s the nub: being stuck largely at home, especially if your house or flat has low levels of natural light, ‘may reduce light-based cues for wakefulness and sleep, known as zeitgebers, which are crucial to our circadian rhythm’.

We are exacerbating this by devoting our nights to light-based screen pursuits – watching news programmes and feeds, binge-watching Netflix, escaping in DStv reruns, doing Zoom conferencing with our family, chatting with friends on WhatsApp, and updating our Facebook posts and blogs. So much screen time can have a detrimental impact on sleep, warns the foundation. Not only can it stimulate the brain in ways that make it hard to wind down, but the blue light from screens can suppress our natural production of melatonin, the hormone the body

‘People who got less than six hours of sleep a night were four times more at risk of catching a cold when exposed to the virus than those who had seven hours or more.’

makes that controls our circadian rhythms, which then helps us sleep, says Dr Bentley. Then in the morning, we’re inclined to sleep in, missing out on the daylight our bodies need.

Dr Bentley echoes what leading sleep researchers internationally are now emphasising: the importance of circadian health. Neuroscientist Dr Steven Lockley, associate professor of medicine at Harvard Medical School and honorary associate professor in sleep medicine at the Clinical Sciences Research Institute at Warwick Medical School in the UK, is a world expert on circadian rhythms and sleep.

‘The absolute key to healthy sleep and circadian rhythms is stable, regularly timed daily light and dark exposure – our natural daily time cues,’ he says in the 2020 Global Wellness Trends Report. ‘After dusk, when natural light disappears, we must minimise the negative impact of man-made light. In the day, we have evolved to be in the light, ideally sunlight, but if not, high-quality blueenriched indoor light. Period. Given that most of our body systems express circadian rhythms, ensuring proper alignment of our internal circadian clocks, starting with the management of lighting will have major impacts on human health.’

Beth McGroarty, director of research at the nonprofit Global Wellness Institute, concludes in the report: ‘While we have been obsessed with sleep and trying to get more of it with smart pillows and tonics, it’s the timing of sleep that is key to getting highquality, restorative sleep. This means sleeping at the right circadian time, and the only solutions that can actually reset circadian rhythms have light at the centre of them.’

The institute predicts a major shift in wellness, focused less on the usual generic sleep solutions, and instead on ‘circadian health optimisation’ – not only for sleep, but for all the brain and body systems controlled by our circadian clock. At a time when it’s been estimated that one in three of us sleeps badly, and one in 10 suffers regularly with insomnia, it’s seldom been more important to get our heads around it – then down on our pillows at the right time.

‘It’s the timing of sleep that is key to getting high-quality, restorative sleep. This means sleeping at the right circadian time.’