How poor sleep affects your weight, mind and energy

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There is a sleep sweet spot

Those who sleep significantly more than seven hours a night, however, are not necessarily spared sleep-related health risks. For optimal health, there seems to be a sweet spot of six to eight hours of nightly sleep. A six-year study of more than 1 million adults ages 30 to 102 by researchers at the University of California, San Diego, and the American Cancer Society revealed a U-shaped curve, with the highest mortality rates among those who slept more than eight hours or less than four hours a night.

In a Nurses’ Health Study that followed 71,617 women for a decade, those who slept eight hours a night had the lowest risk of developing heart disease. But in another study that followed 84,794 nurses for up to 24 years, those who slept nine or more hours a night were twice as likely to develop Parkinson’s disease as those who averaged six hours or less.

Still, many more people, both lay and professional, worry more about too little sleep than an excess of shut-eye, and with good reason. Sleep-deprived people have more accidents and are more likely to fall asleep at inappropriate times, such as at a play or concert or, most seriously, while driving.

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How we sleep may impact how we eat

Although you might expect the opposite, several studies have shown that short sleepers tend to weigh more than those who sleep for longer periods, even though people expend more calories while awake than asleep. A study of 990 working adults in rural Iowa found that the less sleep they got on weeknights, the higher their body mass index tended to be.

A Canadian study of 240 children ages 8 to 17 showed that it was not helpful to try to make up for short weeknights by sleeping longer on the weekend. Fluctuating hours of sleep can impact appetite-regulating hormones in ways that prompt people to eat when they’re not hungry and eat past the point of satiation. The Wisconsin Sleep Cohort Study found that short sleepers had low levels of the appetite-suppressing hormone leptin, and higher levels of the hormone ghrelin, which signals people to eat more.

Furthermore, an attempt to make up for lost sleep on the weekend has been associated with eating in the absence of hunger or in response to fatigue, as well as being unduly tempted by the sight or smell of food. I can attest to a common tendency to eat more — especially snacks of questionable nutritional value — when staying up past what should have been a reasonable bedtime.

Fostering a good night’s sleep

Experts offer a variety of tips for getting a better night’s sleep. Among them:

— Avoid all sources of caffeine in the late afternoon and evening, as well as a big heavy meal close to bedtime.

— Practise good sleep hygiene. Go to bed and get up at about the same time each day.

— Do not use alcohol to help you unwind. Try a warm bath or meditation.

— Reading before bed is great, as long as it’s not on a computer or tablet that emits sleep-inhibiting light.

— If outside light impedes sleep, install light-blocking shades or curtains or use a sleep mask. If noise is a problem, use earplugs or a white-noise machine.

— Consider cognitive behavioural therapy, which challenges underlying thoughts or behaviours that may be keeping you up at night.

This article originally appeared in The New York Times.

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