In today’s fast-paced world, sleep is often treated as optional, something we 'catch up on' over the weekend. Yet science tells us the opposite: sleep is not a luxury; it is a biological necessity. Adequate and good-quality sleep is one of the strongest predictors of long-term health, brain function, and longevity.
How much sleep do we really need?
For most adults, 7–8 hours per night is considered the optimal amount of sleep. Some individuals may function well with slightly less or more, but regularly sleeping less than 6 hours or more than 9 hours is associated with health risks. Children and adolescents need even more sleep, while older adults still require at least 7 hours.
Consistency matters as much as duration
Sleeping and waking at fixed times every day, including weekends, helps synchronise our internal body clock, known as the circadian rhythm. Irregular sleep timing confuses this clock and increases the risk of metabolic, cardiovascular, and mental health problems, even if total sleep duration appears adequate.
Why night-time sleep is the best
Human biology is designed for sleep at night and activity during daylight. Hormones like melatonin, which promote deep and restorative sleep, are released in response to darkness.
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Daytime sleep, even for night-shift workers, is often lighter, fragmented, and less restorative. This explains why shift workers have higher rates of obesity, diabetes, heart disease, and certain cancers. While night-shift workers must sleep during the day, they should aim to optimise sleep conditions. But, it is important to recognise that daytime sleep is not biologically equivalent to night sleep.
What defines good quality sleep?
Good sleep is not just about hours spent in bed. Features of healthy sleep include:
1. Falling asleep within 20–30 minutes
2. Sleeping through the night with minimal awakenings
3. Waking up feeling refreshed and alert
4. No excessive daytime sleepiness
If you wake up tired despite adequate sleep duration, sleep quality may be poor.
Are short power naps helpful?
Short power naps of 20–30 minutes can improve alertness, mood, and productivity. However, long daytime naps (over 60 minutes) or late-afternoon naps can interfere with night-time sleep and should be avoided, especially in people with insomnia.
Diseases linked to short sleep
Chronic sleep deprivation is associated with:
1. Heart attack and stroke
2. High blood pressure
3. Diabetes and obesity
4. Depression and anxiety
5. Dementia and memory decline
6. Weakened immunity
Sleep affects every organ system, from the brain to the heart and metabolism.
Sleep and longevity
Large population studies show that people who consistently get 7–8 hours of good-quality sleep tend to live longer and healthier lives. Sleep allows the brain to clear toxic waste products, the heart to rest, and the body to repair itself. In many ways, sleep is a daily preventive medicine.
Can too much sleep be harmful?
Yes. Habitual oversleeping (more than 9–10 hours) may be linked to poor sleep quality, depression, chronic illness, or undiagnosed sleep disorders. Oversleeping is often a marker of underlying health problems, not a sign of extra rest.
When should you consult a doctor?
Seek medical advice if you experience:
1. Persistent difficulty falling or staying asleep
2. Loud snoring, choking, or breathing pauses during sleep
3. Excessive daytime sleepiness
4. Morning headaches or poor concentration
5. Need for sleeping pills regularly
Many sleep disorders are treatable, but only if recognised.
Sleep is one of the strongest pillars of health, alongside diet and physical activity. Aim for 7–8 hours of consistent, good-quality night-time sleep, limit long daytime naps, and respect your body’s natural clock. Protecting your sleep today is an investment in better health, sharper thinking, and a longer life.
The opinions expressed in this article are those of the author and do not purport to reflect the opinions or views of THE WEEK.