A third of a life, spent well
Sleep is the biggest single thing most of us do. Newborns sleep for most of the day, children for ten hours or more, and adults typically for seven to nine. Add it all up and a large slice of every life is spent with eyes closed, which sounds like lost time until you remember what sleep does: it is when the body repairs itself, memories are sorted and filed, and the brain clears out waste. The clock above shows your usual night as a dark arc on a 24-hour dial, so you can see how much of each day it takes.
The long bar below the result shows your whole life so far. Each slice is a year, shaded by how much of that year we estimate you spent asleep. The dark start is your baby years, when sleep took up more than half of every day.
How we calculate it
For childhood we use typical amounts of sleep by age, based on the ranges sleep organisations recommend: 14 hours a day in the first year, 12.5 at ages one and two, 11.5 from three to five, 10 from six to thirteen and 9 from fourteen to seventeen. From eighteen onward we use the hours between your bedtime and wake-up time. We multiply each by the days you spent at that age and add them up. Dreams are estimated at five per night, the middle of the usual four to six sleep cycles.
| Age | Recommended sleep | Hours we use |
|---|---|---|
| Newborn and infant | 12 to 17 hours | 14 |
| 1 to 2 years | 11 to 14 hours | 12.5 |
| 3 to 5 years | 10 to 13 hours | 11.5 |
| 6 to 13 years | 9 to 11 hours | 10 |
| 14 to 17 years | 8 to 10 hours | 9 |
| Adults | 7 to 9 hours | your hours |
Worked example. A 36-year-old who sleeps from 11 pm to 7 am (eight hours): childhood to 18 adds about 7.9 years of sleep, and the 18.5 adult years at eight hours a night add another 6.2 years. In total they have slept for about 14 years, or 38% of their life.
What the number tells you
Seeing your sleep as years can be a nudge either way. If your nights are short, it is a reminder that adults who regularly sleep less than seven hours tend to feel and perform worse. If your nights are long, it is reassurance that the time is not wasted. Either way, it is the one activity that has been with you every single day of your life.
Questions people ask
How much sleep do adults need?
Sleep organisations such as the US National Sleep Foundation recommend 7 to 9 hours a night for adults aged 18 to 64, and 7 to 8 hours for those 65 and over.
Do we really sleep a third of our lives?
Roughly, yes. Babies and children sleep far more than eight hours, adults often a little less, so over a long life the total usually lands somewhere between a quarter and a third.
How many dreams do we have?
Most adults pass through four to six sleep cycles a night, each ending in a period of REM sleep when vivid dreams are most common. We remember only a small fraction of them.
Do naps count?
They do in real life, but this calculator uses your usual night’s sleep only. If you nap regularly, add the time to your hours with the slider.
Sources. National Sleep Foundation sleep duration recommendations (2015); sleep cycle figures from standard sleep medicine texts. Calculations run in your browser; nothing you enter is sent anywhere.