Do the math
How much of your life do you spend sleeping?
The Simple Answer
About a third. Eight hours of sleep a night is 8 of every 24 hours, so over 80 years you spend about 26.7 of them asleep.
It is a big slice, and it is easy to work out. The only choice is how many hours you sleep.
| Hours a night | Share of your life | Years asleep | Days asleep each year |
|---|---|---|---|
| 7 | 29% | 23.3 | about 107 |
| 8 | 33% | 26.7 | about 122 |
| 9 | 37.5% | 30 | about 137 |
Eight hours a night
8 hours รท 24 hours = one third of each day
One third of 80 years = 26.7 years
In hours: about 234,000 hours, out of roughly 29,200 days
What the CDC recommends
The Centers for Disease Control and Prevention says adults aged 18 to 60 need seven or more hours a night. For ages 61 to 64 it gives seven to nine hours, and for 65 and older, seven to eight. So the range in the table above, seven to nine hours, covers what is recommended for most adults.
The interesting part
At eight hours a night you spend about 122 days of every year asleep, which is four months. Add it up over a lifetime and you will have been awake for roughly 53 years of an 80-year life. The point of the sum is not to make sleep look like lost time. It is a reminder that something you spend a third of your life doing is worth doing well.
Time Duration Calculator: Add or subtract hours and minutes, for example to see how long you slept between two times.
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