Social factors influence sleep. Socioeconomic status may be the most important factor, with longer and better sleep among higher SES groups. The reasons may be related to income, education, healthier life styles and several other issues. Social support is a strong predictor of good sleep. Also, race is related to sleep, with better sleep among whites. Socio-economic status is of importance here, but also unfair treatment. Sleep also deteriorates with increasing age, but alertness increases. Women report more sleep problems than men but sleep physiologically better. Singles in general show more sleep complaints, which may be related to unhealthy life styles and to some extent to social isolation.