Sleep is an essential part of human health and wellbeing. The common belief is that humans spend about one third of our lives sleeping. But is this really true? Let’s take a closer look at the evidence.
How much sleep do humans need?
The amount of sleep humans need varies by age:
| Age | Recommended Hours of Sleep Per Day |
|---|---|
| Newborns (0-3 months) | 14-17 hours |
| Infants (4-11 months) | 12-15 hours |
| Toddlers (1-2 years) | 11-14 hours |
| Pre-schoolers (3-5 years) | 10-13 hours |
| School-age (6-13 years) | 9-11 hours |
| Teenagers (14-17 years) | 8-10 hours |
| Adults (18-64 years) | 7-9 hours |
| Older Adults (65+ years) | 7-8 hours |
These recommendations are from the National Sleep Foundation. As you can see, the amount of sleep needed decreases significantly from infancy to adulthood.
How many hours do adults really sleep?
Actual sleep durations often differ from the recommendations. Here’s a look at average sleep times for US adults from recent survey data:
| Age | Average Hours Slept Per Night |
|---|---|
| 18-25 years | 7.1 hours |
| 26-64 years | 6.8 hours |
| 65+ years | 7.0 hours |
As you can see, adults under 65 sleep about 7 hours per night on average. Adults over 65 sleep around 7-8 hours.
What percentage of life do adults sleep?
Now let’s calculate what percentage of their lives adults spend sleeping:
- Let’s assume an average lifespan of 80 years for adults.
- That’s 80 years * 365 days per year = 29,200 days.
- If adults sleep 7-8 hours per day, that’s:
- 7 hours/day * 29,200 days / 24 hours per day = 8,850 hours slept
- 8 hours/day * 29,200 days / 24 hours per day = 10,133 hours slept
- So adults sleep 8,850 – 10,133 hours over an 80 year lifetime.
- 8,850 hours is about 11% of an 80 year lifetime (8,850 / 80,000 hours).
- 10,133 hours is about 13% of an 80 year lifetime (10,133 / 80,000 hours).
Based on these calculations, adults sleep approximately 11-13% of their lives, not 33%. The one third figure seems to be a myth.
Do we sleep one third of our lives?
In summary, here’s the evidence on whether humans sleep one third of our lives:
- Newborns may sleep up to 50-60% of the time.
- As children grow older, sleep needs decrease dramatically.
- Recommended sleep for adults is 7-9 hours per day, or just under 1/3 of a 24 hour day.
- But adults actually average 7-8 hours of sleep per day.
- Over a typical 80 year lifespan, this works out to only 11-13% of lifetime hours spent sleeping.
So based on current sleep data, it’s false to claim that humans sleep one third of our lives. The one third figure seems to be a myth, especially for adults. Infants may come close to this level of sleep, but sleep time decreases quickly as we age.
Conclusion
While sleep is vital to human health, the belief that people spend close to one third of life sleeping is exaggerated, especially for adults. More accurate estimates are that humans sleep around 11-13% of our lives on average. So although sleep remains important, the one third claim seems to be a myth not supported by scientific evidence on actual sleep patterns across the lifespan.