Lack of sleep: Why it smashes immune systems and harms your brain

If someone promised you a revolutionary new treatment that made you live longer, boosted your memory and creativity, kept you slim and made you better looking, would you be interested? And wait, it also helps guard you from cancer and dementia, lowers your risk of heart attacks, stroke and diabetes, and keeps away colds and the flu. Sound good? You’ll even feel happier, less depressed and less anxious. Of course you’d take it. It’s just sleep. Eight hours a night of solid, uninterrupted sleep.

Chances are very good you know someone with sleep problems. Casual chats with your friends will reveal someone who has difficulty getting to sleep, another who wakes and meditates in the pre-dawn hours to lure back drowsiness, another who takes melatonin most nights, one who uses her awake time to read and another who regularly takes sleeping pills. Insomnia affects women more than men, and more than a third of NZ adults report never or rarely getting enough sleep. A 2012 study, published in the NZ Medical Journal, estimated that about 13% of the adult population under 60 frequently suffered insomnia, though Māori were over-represented at 19.1% (partly explained, it said, by greater socio-economic deprivation and more night work) compared with 8.9% for non-Maori, and the proportion of the population with serious and regular sleep problems is certainly far higher.

“You’d expect that that’s gone up, says Massey University sleep researcher Professor Philippa Gander, one of the authors of the research. The study put the cost of insomnia at about $28m a year, though that’s likely to be conservative given the effect on people’s physical and mental health, work and family life. Oh, and the funding available in the New Zealand health-care system for the treatment of insomnia? “Zero dollars, says Gander, director of the university’s sleep/wake research centre.

Services for people with sleep disorders here are “woefully inadequate”, she says. Often, the only thing GPs have in their arsenal is sleeping pills. “Internationally, that’s not the No 1 treatment. That’s cognitive behaviour therapy (CBT).” In CBT, the patient works with a therapist over a number of weeks, building on basic principles such as reducing screen time, caffeine and alcohol, regular bedtime and wake-up, going to bed only when sleepy and not remaining in bed if awake - with methods individualised for the patient, their problems and lifestyle. Numerous clinical studies have proven CBT for insomnia (CBT-I) is superior to sleeping pills for onset, length and quality of sleep.

Some sleep clinics provide CBT-I in New Zealand. In Australia, says Gander, GPs have the option of referring a patient with insomnia to a registered psychologist for treatment under the Medicare mental health care programme. In the UK, the National Health Service covers CBT-I with or without a GP referral.

There are lots of causes of insomnia, Gander says, from external issues to problems with brain function, which need to be diagnosed carefully and take into account the non-sleeper’s behaviours and beliefs. “We really have a huge problem with insomnia in New Zealand. A big part of this is a failure to recognise, at all levels of society, politically, medically, the importance of sleep,” says Gander, who in past decades worked for Nasa in its fatigue countermeasures programme monitoring pilots. “We need to drop this idea that to get more out of a busy life we can cut back on sleep. You can’t just expect that a third of your life doesn’t matter and expect that everything else will go fine. Sleep is an essential part of being fully human.”

Matthew Walker, a professor of neuroscience and psychology at University of California, Berkeley, and a sleep scientist at Google, lays out the full catastrophe based on the latest scientific studies, brain scans and epidemiological data. Routinely sleeping less than six or seven hours smashes our immune systems, more than doubling the risk of cancer, he says. It is a key lifestyle factor in determining whether we develop Alzheimer’s disease. Undersleeping increases the likelihood of furred and brittle arteries, ferrying us towards heart attacks and strokes, says Walker. Even moderate reductions of sleep for a week can disrupt blood-sugar levels so severely that a person can be classified as prediabetic. Sleep disruption contributes to all major psychiatric conditions including depression and anxiety. It lowers testosterone levels and sperm counts in men; reduces follicular-releasing hormones in women, greatly impacting their fertility; messes with menstrual cycles and increases the risk of miscarriage.

It makes it easier to gain weight and harder to lose it - swelling concentrations of a hormone that makes you feel hungry while suppressing another that makes you feel full. Sleep loss makes us tired and groggy, anxious, and more prone to accidents. Gander cites an early 2000s study which found that injury accidents on Auckland roads could be reduced by an astonishing 19% if people avoided driving when they felt sleepy, if they’d had less than five hours’ sleep in the previous 24 hours, or between 2am and 5am, when the physiological sleep drive peaks.

Gander is the lead author of a three-year study into managing fatigue and shift work in hospital-based nursing - a draft code was released for consultation in early December. It’s connected to a long-term study tracking more than 70,000 nurses who do a minimum of three night shifts a month. Even at this frequency, over time they are more likely to develop breast, lung and colorectal cancers, type 2 diabetes, cardiovascular disease and to become obese. “The picture is not pretty, and the data in that particular longitudinal survey is absolutely compelling,” she says. The findings could be useful in other shiftworking occupations such as truck driving.