We share a long evolutionary history of sleep with other animals.
Sleep is essential for learning and thinking. Physiological and neural mechanisms rest and reset ready for the next day. Memories are sorted and consolidated. We go to bed with a problem and awake with a solution.
deprivation
Disrupted sleep or sleep deprivation worsens frustration, confusion, stress, depression, mental ability, reaction times and sensitivity to pain. Physical health deteriorates.
Without sleep our world disintegrates into a kaleidoscope of fragmented dream-like images. And extreme long term sleep deprivation leads to physical and mental breakdown, paranoia, depression and hallucinations.
how much
Everyone is different. Some need as little 5 hours, others as much as 10. If we feel drowsy during the day, maybe we haven’t had enough sleep or maybe we have a health problem.
Infants generally need about 16 hours a day.
Teenagers about 9 hours.
Adults, 7 to 8 hours.
Women in the first 3 months of pregnancy often need more.
We tend to sleep more lightly and for shorter time spans as we get older, although we generally need about the same time asleep as in early adulthood.
More sleep is needed if sleep has been inadequate in the previous few days. A few days of adequate sleep makes up for a long time of sleep deprivation.
just enough
Sufficient sleep is enough. More may be wasted time. Less sleep is needed when we are relaxed and active. Exercise or meditation can reduce the need for sleep including the binaural meditation on the mind pages.
good sleep
After a period of stress and sleeplessness we may forget how to fall asleep or learn to expect sleeplessness. A bit of practice and a few experiences of success may be all that is needed. A holiday can shake off old habits. Exhausting activities can make sleep irresistible.
It is almost always possible to achieve good sleep using the sleep hints and links on the side-menu and the relaxation exercises on the stress pages.