The shorter your sleep, the shorter your life: the new sleep science

Everyone feels better after a good night’s rest. Now, neuroscientist Matthew Walker says sleep deprivation is increasing our risk of cancer, heart attack and Alzheimer’s. And he might be right. More than 20 large-scale epidemiological studies report the same clear results: the shorter your sleep, the shorter your life.

For example, adults aged 45 years or older who sleep less than six hours a night are 200% more likely to have a heart attack or stroke in their lifetime, as compared with those sleeping seven or eight hours a night. (Why? Part of it is blood pressure. Lack of sleep increases blood pressure, placing more stress on your cardiovascular system.)

A lack of sleep also appears to hijack the body’s control of blood sugar. Your cells become less responsive to insulin and can cause a prediabetic state of hyperglycemia. Also, you become susceptible to weight gain: inadequate sleep decreases levels of the satiety-signalling hormone, leptin, and increases levels of the hunger-signaling hormone, ghrelin.

Further, sleep deficits weaken the immune system and may accelerate the onset of degenerative neurological conditions like Alzheimer’s.

Fast Facts

  • Two-thirds of adults in developed nations fail to obtain the nightly eight hours of sleep recommended by the World Health Organisation.
  • An adult sleeping only 6.75 hours a night would be predicted to live only to their early 60s without medical intervention.
  • If you drive a car on less than five hours’ sleep, you are over 400% times more likely to be involved in a car accident. If you drive with only four hours, you are 11.5 times more likely to be involved in an accident.
  • There are now more than 100 diagnosed sleep disorders. Insomnia is the most common.
  • A 2013 study reported that men who slept too little had a sperm count 29% lower than those who regularly get a full and restful night’s sleep.
  • The time taken to reach physical exhaustion by athletes who obtain anything less than eight hours of sleep, and especially less than six hours, drops by 10-30%.
  • Morning types, who prefer to awake at or around dawn, make up about 40% of the population. Evening types, who prefer to go to bed late and wake up late, account for about 30%. The remaining 30% are in the middle.

So what can you do? First, they should avoid pulling “all-nighters”, at their desks or on the dancefloor. After being awake for 19 hours, you’re as cognitively impaired as someone who is drunk. Second, you should start thinking about sleep as a kind of required activity, like going to the gym. Sleep is just something you have to do, if you want to live a long, healthy life.

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