When is more or less sleep required? A study of variable sleepers.
D003863:Depression / Q000150:complications; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D008593:Menopause; D008598:Menstruation; D009790:Occupations; D005082:Physical Exertion; D012737:Sex Factors; D012890:Sleep; D013315:Stress, Psychological; D013850:Thinking; D013997:Time Factors