Due to the calm and peaceful environment, one feels like they are resting at night. Bright light and a warm environment during the day have energizing benefits and keep a person awake and paying more attention. The environment and noise have a role in this as well.
Normally a newborn baby sleeps continuously for 3 hrs. then wakes up, takes food, plays, passes urine and stools and after about half an hour goes to sleep again. Thus a newborn baby has 7 to 8 cycles of sleep and wakefulness in day and night. Its developing, growing and immature brain requires 18-20 hrs. of sleep.
During the day, the sattva quality regulations, keep the person active. On the other hand, during night, tamas quality rules and is sleep-friendly.
A sattvic person requires 4-6 hours of sleep each night. A rajasic person needs 8 hours of sleep, but a tamasic person—whose mind is weak and quickly tired out—needs 10 to 12 hours.
The BMR significantly drops and the catabolic processes never exceed the anabolic processes in samadhi, the ultimate state of meditation. As a result, a Yogi who has perfected meditation does not need to sleep at all.
