This is why we sleep less as we get older, science explains

Around the age of 40, the average amount of sleep we get decreases every 10 years by 30 minutes. This means that elderly people tend to get up early, and here's why it happens.

Every ten years our sleep decreases by this much, here's why
© Simon Berger / UNSPLASH
Every ten years our sleep decreases by this much, here's why

Sleep is a fundamental pillar of a healthy life, and a main factor of good health. According to the French publication Institut National du Sommeil et de la Vigilance, from adulthood onwards, we are recommended to sleep 7 hours or more per night. This is advised for those between the ages of 18 and 60.

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This recommendation for sleep duration changes a little, and becomes more precise in terms of age: between the ages of 61 and 64, 7 to 9 hours of sleep per day are recommended. From the age of 65 onwards, 7 to 8 hours a day are recommended.

However, as people start to reach their forties, the average amount of sleep they get decreases by 30 minutes every 10 years. This is due to a physiological phenomenon that takes place in the brain.

It's all in the mind....

'The brain reacts less, and loses speed as we age,' Dr. Sairam Parthasarathy, Director of the Sleep Center and Professor of Science at Arizona Health Sciences University, told Huffpost. An older person's brain willreact less quickly and less well to sunset and sunlight, to mealtimes (no feeling of hunger), and to social cues that are markers of the time and progress of day. So, for a younger person, dinnertime can help the brain understand that bedtime is a few hours away. But for an older person, this connection may not occur.

The nerves which are supposed to give the brain clues to time undergo degeneration resulting in an inability to 'perceive temporal cues', which explains why the elderly tend to tire before their children or grandchildren, and consequently go to bed and wake up earlier than everyone else.

... but also in the eyes

Another reason for this shift in the sleep cycle seems to be that the changes in vision that occur with age reduce the intensity of the degree of light stimulation our brains receive, which plays an important role in 'tuning' our circadian clock and keeping it on track

Cindy Lustig, professor of psychology at the University of Michigan, told Huffpost.

According to Dr. Sairam Parthasarathy, this is especially true for people suffering from cataracts, a progressive opacification of the crystalline lens inside the eye. This eye disease affects more than half of all people over 65, and more than two-thirds of those over 75, regardless of gender.

According to the NHS, signs of cataracts include blurred eyesight, sensitivity to light, difficulty seeing in low light, and colours seeming faded.

This article has been translated from Gentside FR.

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Sources used:

Institut National du Sommeil et de la Vigilance

IFL Science: Why Do Adults Wake Up Earlier As They Get Older?

Huffpost: Why You Wake Up Earlier As You Get Older


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