Kung hunter-gatherers in Africa, Swat Pathan herders in Pakistan, and Balinese farmers in Indonesia. For all these groups and six others, communal sleep equals safe sleep, because sleepers can count on there being someone else up or easily awakened at all hours of the night to warn others of a threat or emergency. Adult sleepers in traditional societies recline on skins, mats, wooden platforms, the ground, or just about anything except a thick, springy mattress. Pillows or head supports are rare, and people doze in whatever they happen to be wearing. Virtually no one, including children, keeps a regular bedtime.
Individuals tend to slip in and out of slumber several times during the night.
In these unplugged worlds, darkness greatly limits activity and determines the time allotted to sleep. Folks there frequently complain of getting too much sleep, not too little. Many rituals occur at night and exploit the need to sleep. For instance, initiation rites often force participants to cope with sleep deprivation. In other ceremonies, individuals enter somnolent, or near-sleep, states in order to magnify an occasion's psychological impact and to induce spiritual visions.