Health

Is sleep anti-evolutionary?

It may seem like sleep is a mistake because we spend about a third of our lives in a state in which our pre-agrarian ancestors could have been attacked and killed by animals. But “evolution does not make mistakes,” says Dr Abhinav Singh, the facility director at the Indiana Sleep Center, US.

Humans, however, disrupted sleep with the invention of light bulbs, industrialisation, and becoming an always-on culture, where responding to emails at 2 am is celebrated. It’s only over the past couple of decades that sleep has become a subject to study, a matter to take seriously, because we’ve understood the perils of not getting enough.

“We are all solar animals, designed to be charged by the sun, and to recuperate at night,” says Dr Singh. This means that our bodies are governed by circadian rhythm: waking with the rise of the sun, drumming down activity with the setting of the sun, and sleeping as darkness descends. “Every cell of our body responds to wake-sleep mode. Every living being — plants and animals too — have a rest and activity cycle,” he says. Each organ needs sleep to repair, restore, rejuvenate, and refresh itself, body and mind.

Here, Dr Singh tells us how to get a good night’s rest.

Determine your ‘sleep number’. The number of hours you need to sleep is different for everyone. “If you allow yourself to naturally fall asleep and wake up for about two weeks — without alarms and extra screen exposure in the evening — you will realise what your number is,” says Dr Singh. Adults usually fall in the seven-to-nine hour range. Six hours or less has been shown to have deficits of all kinds: cognitive, memory, mood issues, forgetfulness.

Skip the calories after sundown. “Any calories eaten after sunset is going to be troublesome, particularly applicable for calorie dense meals after dark,” he says, adding that if you sleep poorly your signals to eat more are higher because the body feels that it is under threat of survival. Eating fibre-rich foods like fruit and nuts can help cut back on calories at night. Definitely skip fatty, sugar-filled, packaged foods, and alcohol. “Alcohol acts in the same place as Valium does in the brain. It may help you feel a little drowsy, but in the second half of the night, the breakdown products of alcohol act like darts into the brain. It is disruptive and reduces the brain’s ability to get into deep sleep. One glass of wine three hours before sleeping is okay.”

Switch off screens at sundown. Or at the very least, an hour before bedtime. Any kind of light — even if you have a blue light filter — sends a signal of wakefulness to the brain, delaying sleep onset. Convert your night relaxation into something you can listen to: an audio book or gentle music, for instance.

Set the scene. “Let sleep come to you, rather than chasing it,” says Dr Singh, describing sleep as a butterfly — it wil come to you if you keep your body and mind very still. Cue darkness, quietude, an environment where you feel cool enough to feel the need for a sheet. “Cold temperatures help your body release melatonin. It helps your surface temperature rise. As the blood vessels dilate, they lose heat and your core cools down,” he says, describing how sleep comes on.

Remember ‘sleep foreplay’. About 90 minutes before you sleep make sure you’ve dealt with all that you need to, in terms of work and chores, and begin to wind down. Then take a shower, journal for about 15 minutes, plan for the next day, read, breathe, and focus on your breath.

Take mid-afternoon naps. Somewhere between the hours of noon and 3 pm, we feel a lull in alertness. “You can’t keep your engine running at full throttle for 16 hours, so nature has planted this,” says Dr Singh, who advises a shut-eye for 20 to 25 minutes, whether you sleep or not. “The sugar and caffeine cravings go away. If you’re a parent and need to fragment your sleep into say six hours at night and two hours in the daytime, do so for a year or so, but try to get out of the cycle as soon as possible.”

Check with your doctor if you’re snoring. It could be sleep apnoea and means you’re losing breath. “Have it evaluated especially if you have a dry mouth, feel sleepy during the day, or drink lots of caffeine to stay awake,” says Dr Singh.

Use props. If you need an app like Calm or Headspace, go for it. Avoid apps that are asking you to interact and engage. There’s no harm using white noise or pink noise machines either. If you feel essential oils like lavender helps you, try it as long as it doesn’t cause an allergy, though there’s no large-scale scientific research to support this.

Understand why productivity at work and sleep are linked. A rested employee takes less time to finish a task and makes fewer errors than someone who is sleep deprived, making the system more efficient. Dr Singh talks of absenteeism, where the employee may take more leave because of problems resulting from poor sleep. He says presenteeism is worse, when the person is physically present but absent mentally, often tired and caffeinated.

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Printable version | Nov 29, 2020 10:48:18 PM | https://www.thehindu.com/sci-tech/health/is-sleep-anti-evolutionary/article32963725.ece

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