There is a common stereotype of teenagers sleeping into the afternoon but older adults getting up at the crack of dawn. It turns out that there seems to be a pinch of truth in this stereotype, and it is in fact part of the natural aging process.
It is recommended by experts that people get seven or more hours of sleep per night and that they should be going to sleep at the same time each evening. However, as a person starts to creep into midlife, the average amount that people sleep at night decreases by 30 minutes every 10 years, and they also tend to go to bed earlier and wake up sooner.
There are many reasons why this can happen.
It’s all in the brain
The pattern of aging and sleeping and waking earlier is mainly to do with the brain. Like many parts of our body, the brain just isn’t as responsive as we get older.
“The wiring of the brain is likely not sensing ... and responding to the inputs as well as it should because it’s an aging brain,” Dr. Sairam Parthasarathy, the director of the Center for Sleep and Circadian Sciences at the University of Arizona Health Sciences, told HuffPost.
These inputs are markers that help us determine where we are in a day, like daylight, social cues, mealtimes, and physical activity. If you are locked in a room with no light or food, apart from being a form of torture, it would also be very difficult to determine what day and time it was.
For teenagers, their brains are receiving these cues. However, for older adults, these cues are not linking up in the brain, due to natural brain degeneration. This is also one reason why older people get tired earlier than the younger generation and may require them to snuggle up in bed earlier, and therefore wake up earlier too.
It’s also all in the eyes
The eyes also play a major part in receiving external cues and, of course, vision changes with age.
“Interestingly, one of [the reasons] seems to be that the vision changes that come with age reduce the intensity of the degree of light stimulation that our brain receives, which plays an important role in ‘setting’ our circadian clock and keeping it on track,” said Professor Cindy Lustig, a member of the cognition and aging laboratory at University of Michigan.
This also affects people who may have cataracts, a common condition that normally affects the older generation. As the disease progresses, the lens inside the eye develops cloudy patches.
“If there's cataracts, the evening light doesn’t go into the eyes as much, so, according to the brain, sunset is earlier than when it actually set,” said Parthasarathy.
This in turn affects melatonin levels in the body. Melatonin is also known as the sleep hormone, and normally starts increasing once the sun sets. If the presence of cataracts makes the brain think that the sun sets earlier than it actually has, it can cause melatonin levels to rise prematurely and make you want to go to sleep earlier.
Overall, going to bed earlier and waking up earlier is a natural part of aging – even if you identify as a night owl in your younger days.
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