Sleep is an essential biological need
Many people see sleep as something that can be reduced and then "compensated" on weekends. However, according to Dr. BK Madhusudhan, Leading Consultant - Department of Neurology at Aster RV Hospital, Bangalore (India), sleep is an important biological need, not just a simple rest time. When sleeping, the body repairs tissues, balances hormones and eliminates cell waste in the brain.
From birth to old age, sleep plays different but essential roles. Young children need to sleep a lot to develop their brains, while adults need to sleep enough to strengthen memory, maintain immunity and prevent chronic diseases.
Four stages of a sleep cycle
A normal night's sleep consists of many cycles, each cycle lasting about 90 minutes and repeated 4–6 times.
NREM 1 (light sleep): Lasts 5–10 minutes, the body begins to relax but is still easily awakened.
NREM 2: Accounts for nearly half of the sleep time, slows heart rate, reduces body temperature, supports information processing and memory.
NREM 3 (deep sleep): Recovery stage, the body repairs tissues, strengthens immunity and develops skeletal muscles. When older, deep sleep time usually decreases.
REM (dreaming): Appears about 90 minutes after sleep, helps regulate emotions and supports learning. The brain is active but muscles are temporarily relaxed to avoid dreamy movements.
Recommended sleep time by age
According to experts, sleep needs change with each stage of life:
0–3 months: 14–17 hours
4–12 months: 12–16 hours
1–5 years: 10–14 hours
6–12 years old: 9–12 hours
13–18 years old: 8–10 hours
19–64 years old: 7–9 hours
Over 65 years old: 7–9 hours
The younger the person, the more sleep they need. Most healthy adults need 7–9 hours per night to function optimally.
Not just the number of hours, quality is also important
Dr. BK Madhusudhan said that getting enough sleep but waking up often can still prevent the body from achieving the necessary deep sleep. In addition, pregnancy, stress, prolonged sleep deprivation, or aging also change sleep needs. Frequent sleep deprivation, especially less than 7 hours per night in adults, is associated with weight gain, risk of diabetes, cardiovascular disease, high blood pressure, stroke, depression, and anxiety.
How do you know you are getting enough sleep?
In addition to sleep hours recommendations, the simplest assessment is based on your condition during the day. If you wake up feeling alert, working focused and maintaining stable energy until the end of the day, you may have slept enough. Maintaining regular and quality sleep each night is an important factor in protecting long-term health.
