Access to electric light is associated with shorter sleep duration in a traditionally hunter-gatherer community

DE LA IGLESIA HO; FERNANDEZ DUQUE E; GOLOMBEK DA; DUFFY J; CZEISLER C; VALEGGIA C

JOURNAL OF BIOLOGICAL RHYTHMS.

SAGE PUBLICATIONS INC

Año: 2015 vol. 30 p. 342 - 350

0748-7304

Access to electric light might have shifted the ancestral timing andduration of human sleep. To test this hypothesis, we studied two communitiesof the historically hunter-gatherer indigenous Toba/Qom in the ArgentineanChaco. These communities share the same ethnic and sociocultural background,but one has free access to electricity while the other relies exclusivelyon natural light. We fitted participants in each community with wrist activitydata loggers to assess their sleep-wake cycles during one week in the summerand one week in the winter. During the summer, participants with access toelectricity had a tendency to a shorter daily sleep bout (43 ± 21 min) than those living under natural light conditions. This difference was due to a later daily bedtime and sleep onset in the community with electricity, but a similar sleep offset and rise time in both communities. In the winter, participants without access to electricity slept longer (56 ± 17 min) than those with access to electricity, and this was also related to earlier bedtimes and sleep onsets than participants in the community with electricity. In both communities, daily sleep duration was longer during the winter than during the summer. Our fieldstudy supports the notion that access to inexpensive sources of artificial lightand the ability to create artificially lit environments must have been key factors in reducing sleep in industrialized human societies.