Is 6 Hours of Sleep Enough? What the Research Says
For most adults, 6 hours of sleep is not enough. The American Academy of Sleep Medicine (AASM) and the Sleep Research Society recommend 7 or more hours a night for adults aged 18 to 60. A few people genuinely need less, but they are rare, and research shows that people who sleep 6 hours a night often underestimate how much it is affecting them.
Key facts
- Adults need at least 7 hours of sleep a night, according to the AASM and the Sleep Research Society.
- About 35% of US adults sleep less than 7 hours, according to CDC survey data for 2022.
- In a lab study, people limited to 6 hours a night for two weeks performed as badly on attention tests as people kept awake for a night or two, but felt only slightly sleepy.
- Regularly sleeping less than 7 hours is linked to weight gain, high blood pressure, diabetes, depression and accidents.
What the experts recommend
In 2015, a panel of 15 sleep experts reviewed more than 5,000 scientific papers to agree on how much sleep adults need. Their conclusion: adults should sleep 7 or more hours per night on a regular basis. Sleeping more than 9 hours may be appropriate for young adults, people recovering from sleep loss and people who are ill.
| Age | Recommended sleep | Is 6 hours enough? |
|---|---|---|
| Teen (13–18) | 8–10 hours | No |
| Adult (18–60) | 7 or more hours | No, for most people |
| Adult (61–64) | 7–9 hours | No |
| 65 and older | 7–8 hours | No, for most people |
Sources: AASM (teens and adults up to 60) and National Sleep Foundation (61 and older), as published by the CDC.
The 6-hour experiment
One of the best-known studies of short sleep was carried out by Hans Van Dongen and colleagues at the University of Pennsylvania and published in 2003. Healthy adults spent two weeks in a laboratory with their sleep restricted to 4, 6 or 8 hours a night, while another group stayed awake for three nights in a row.
The 6-hour group’s performance on attention and memory tests got steadily worse over the two weeks. By the end, they were doing as badly as people who had gone without sleep for one or two full nights. Yet when asked how sleepy they felt, they rated themselves as only slightly sleepy.
That gap between how impaired you are and how impaired you feel is the main reason 6 hours is risky: you adapt to feeling tired, but your reaction time and concentration don’t.
What regular short sleep is linked to
According to the AASM and Sleep Research Society consensus, sleeping less than 7 hours a night on a regular basis is associated with:
- weight gain and obesity
- diabetes
- high blood pressure, heart disease and stroke
- depression
- a weaker immune system and more pain
- poorer performance at work and more errors
- a greater risk of accidents, including drowsy driving
Most of this research shows associations rather than proving that short sleep causes each problem, but the pattern is consistent across many large studies.
Are some people fine on 6 hours?
A very small number of people have a natural “short sleeper” trait and feel fully rested on 6 hours or less. Researchers have linked it to rare gene variants. It’s far less common than the number of people who think they have it.
A simple test: on a holiday with no alarm, how long do you sleep after the first few days? If it’s 7 to 8 hours, that’s what your body needs.
How to get from 6 to 7.5 hours
- Move your bedtime earlier by 15 minutes every few nights, rather than an hour at once.
- Keep the same wake-up time every day, including weekends.
- Stop caffeine at least 6 hours before bed. Our caffeine cut-off calculator works out the time for you.
- Use the sleep calculator to pick a bedtime that gives you 5 full sleep cycles.
- If you can’t get more sleep tonight, a 10 to 20-minute nap in the early afternoon can help.
Sources
- Watson NF et al. Recommended amount of sleep for a healthy adult. AASM and Sleep Research Society, Journal of Clinical Sleep Medicine, 2015
- Van Dongen HPA et al. The cumulative cost of additional wakefulness. Sleep, 2003
- Centers for Disease Control and Prevention: About sleep
- America’s Health Rankings: Insufficient sleep (CDC BRFSS data, 2022)
Frequently asked questions
Is 6 hours of sleep enough for one night?
One short night won’t do lasting harm, but you will probably be less alert the next day. It’s the regular pattern that matters.
Is 6 hours of sleep better than 7 if it lines up with sleep cycles?
No. Waking between cycles can help you feel less groggy, but it doesn’t make up for an hour and a half less sleep. Aim for 7.5 hours (5 cycles) instead.
How much sleep do you need to function?
Most adults function best on 7 to 9 hours. Below 7 hours, attention and reaction time decline, even if you don’t notice it.
