In this section, we present the theory and practice of sleep which current scientific evidence has convinced us is most conducive to a healthy, happy and long life. Individual humans have enormous genetic variation which is additionally compounded by the alterations of development and the modifications wrought by external insults during a long life-time. In addition, they have a life-time of highly varied acquired tastes regarding their activities. Therefore no one regimen of sleep types and amounts will be either satisfying or optimal for the health and longevity of everyone. We make allowance for that by suggesting alternatives, within reasonable bounds, which we think can fully satisfy the needs of both the body and the mind while still being compatible with maximizing the Lifetime Happiness of the individual.
A medical textbook definition of sleep is unconsciousness from which the person can be aroused by sensory or other stimuli distinguished from coma, which is unconsciousness from which the person cannot be aroused. (Guyton, Textbook of Medical Physiology, Ch 59, 1999)
The aspects of sleep which are important for health and longevity can only be determined from the benefits and harms which are shown by experimental research to accrue from those aspects of sleep. A study of the research literature strongly suggests that the following aspects of sleep are of paramount importance: