How much sleep do adults actually need?
Most adults need 7–9 hours of sleep per night. Here's what happens when you get less, why the 'I function fine on 6 hours' belief is usually wrong, and how to improve your sleep.
2 min read · Updated 2026-04-14
For informational purposes only. This content is not a substitute for professional medical advice. Always consult a qualified healthcare provider before making health decisions.
Short answer
Adults need 7–9 hours of sleep per night. The National Sleep Foundation and CDC both agree on this range. People who say they function fine on 5–6 hours are usually mistaken — studies show sleep-deprived people dramatically underestimate their impairment.
Sleep needs by age group
| Age group | Recommended hours | |-----------|------------------| | Newborns (0–3 months) | 14–17 hours | | Infants (4–11 months) | 12–15 hours | | Toddlers (1–2 years) | 11–14 hours | | Preschool (3–5 years) | 10–13 hours | | School age (6–13 years) | 9–11 hours | | Teens (14–17 years) | 8–10 hours | | Adults (18–64 years) | 7–9 hours | | Older adults (65+) | 7–8 hours |
What happens when you sleep less than 7 hours
Short-term (days):
- Slower reaction time
- Impaired decision-making and creativity
- Increased irritability and emotional reactivity
- Higher caloric intake (sleep deprivation increases hunger hormones)
Long-term (months/years):
- Increased risk of obesity, type 2 diabetes, and heart disease
- Weakened immune system
- Higher risk of depression and anxiety
- Cognitive decline
The "I'm fine on 6 hours" myth
Research from the University of Pennsylvania showed that people restricted to 6 hours per night performed as poorly as people who were completely sleep-deprived for 24 hours on cognitive tests — but they reported feeling only slightly sleepy.
The brain adapts to feeling sleepy, but performance deficits don't adapt. You get used to feeling tired, not to performing well.
How to improve sleep quality
- Consistent schedule: Same bedtime and wake time every day, including weekends
- Cool room: 65–68°F (18–20°C) is optimal for sleep
- Avoid screens 1 hour before bed: Blue light suppresses melatonin
- No caffeine after 2pm: Caffeine has a 5–6 hour half-life
- Dark room: Blackout curtains or a sleep mask
- Avoid alcohol as a sleep aid: It reduces sleep quality even if it helps you fall asleep faster
When to see a doctor
Talk to a doctor if you:
- Sleep 7–9 hours but still feel exhausted
- Snore loudly or wake up gasping (possible sleep apnea)
- Can't fall asleep despite being tired most nights
- Feel your legs must move when trying to sleep (restless leg syndrome)