Changes

Some societies display a fragmented sleep pattern in which people sleep at all times of the day and night for shorter periods. In many [http://en.wikipedia.org/wiki/Nomadic nomadic] or [http://en.wikipedia.org/wiki/Hunter-gatherer hunter-gatherer] societies, people will sleep on and off throughout the day or night depending on what is happening.  Plentiful artificial [[light]] has been available in the industrialised West since at least the mid-[http://en.wikipedia.org/wiki/19th_century 19th century], and sleep patterns have changed significantly everywhere that lighting has been introduced.  In general, people sleep in a more concentrated burst through the night, going to sleep much later, although this is not always true.

Some societies display a fragmented sleep pattern in which people sleep at all times of the day and night for shorter periods. In many [http://en.wikipedia.org/wiki/Nomadic nomadic] or [http://en.wikipedia.org/wiki/Hunter-gatherer hunter-gatherer] societies, people will sleep on and off throughout the day or night depending on what is happening.  Plentiful artificial [[light]] has been available in the industrialised West since at least the mid-[http://en.wikipedia.org/wiki/19th_century 19th century], and sleep patterns have changed significantly everywhere that lighting has been introduced.  In general, people sleep in a more concentrated burst through the night, going to sleep much later, although this is not always true.

In some [[societies]], people generally sleep with at least one other person (sometimes many) or with [[animals]]. In other cultures, people rarely sleep with anyone but a most [[intimate]] [[relation]], such as a spouse. In almost all societies, sleeping partners are strongly regulated by [[law|social]] [[standards]]. For example, people might only sleep with their immediate [[family]], extended family, spouses, their [[children]], children of a certain age, children of specific [[gender]], [[peers]] of a certain gender, [[friends]], peers of equal social rank, or with no one at all. Sleep may be an actively social [[time]], depending on the sleep groupings, with no constraints on noise or activity.[56]

In some [[societies]], people generally sleep with at least one other person (sometimes many) or with [[animals]]. In other cultures, people rarely sleep with anyone but a most [[intimate]] [[relation]], such as a spouse. In almost all societies, sleeping partners are strongly regulated by [[law|social]] [[standards]]. For example, people might only sleep with their immediate [[family]], extended family, spouses, their [[children]], children of a certain age, children of specific [[gender]], [[peers]] of a certain gender, [[friends]], peers of equal social rank, or with no one at all. Sleep may be an actively social [[time]], depending on the sleep groupings, with no constraints on noise or activity.

People sleep in a variety of locations. Some sleep directly on the ground; others on a skin or blanket; others sleep on platforms or beds. Some sleep with blankets, some with pillows, some with simple headrests, some with no head support. These [[choices]] are shaped by a variety of factors, such as climate, protection from predators, housing type, [[technology]], and the incidence of pests.[56]

People sleep in a variety of locations. Some sleep directly on the ground; others on a skin or blanket; others sleep on platforms or beds. Some sleep with blankets, some with pillows, some with simple headrests, some with no head support. These [[choices]] are shaped by a variety of factors, such as climate, protection from predators, housing type, [[technology]], and the incidence of pests.[56]