How Much Sleep Do Adults Need? Experts Explain The 7-9 Hour Range
Eight hours can be adequate, but sleep needs vary individually.
The commonly followed recommendation that adults should get eight hours of sleep every night may be too simplistic, according to recent research. A new review published in Brain Medicine examines how sleep duration, timing and regularity vary across individuals and societies. The researchers argue that there is no single sleep duration that necessarily applies to every adult, while emphasising that sleep remains essential for physical and mental well-being.
The review draws on research into sleep patterns among people living in pre-industrial societies. A study published in Current Biology found that members of communities in Tanzania, Namibia and Bolivia slept for between 5.7 and 7.1 hours a night on average. Researchers observed that participants generally woke close to dawn without relying on alarm clocks and did not compensate for shorter nighttime sleep through lengthy daytime naps.
The findings also point to the influence of modern lifestyles on sleep. According to the review, industrialisation, electrification and urbanisation have changed sleep timing, duration and regularity by altering exposure to natural light and introducing artificial illumination. Night-shift work and other modern routines can further disrupt the body's circadian rhythm, potentially affecting physical and mental health.
Also Read: Struggling To Sleep? Your Dinner Drink Could Be Part Of The Problem
Research cited by The Conversation and Royal Society Publishing also indicates that sleep patterns in pre-industrial societies differed from those commonly seen today. One estimate put average sleep duration in such societies at around 6.4 hours per night, while modern sleep schedules are often delayed compared with natural light-dark cycles. Many people now sleep less during working days and attempt to compensate by sleeping longer on weekends.
Another study published in Nature examined the relationship between sleep and the ageing of different organs using brain and body scans as well as molecular measures. The research estimated an ideal sleep range of roughly 6.4 to 7.8 hours, depending on factors including sex and the particular organ being assessed. The findings reinforce the idea that sleep needs can vary rather than fitting neatly into a universal eight-hour target.
Researchers therefore emphasise that sleep quality, consistency and timing should be considered alongside total hours. Going to bed and waking up at relatively consistent times can help support the body's circadian rhythm. While additional sleep on weekends may help with short-term tiredness after insufficient sleep, maintaining a regular sleep schedule throughout the week remains an important part of healthy sleep habits.
Also Read: Donald Trump Gains 10.4 Kg In 3 Years: What Experts Say About Weight Gain In Older Adults
