The influence of age- and sex-specific labor demands on sleep in Namibian agropastoralists

Sleep timing and duration in indigenous villages with and without electric lighting on Tanna Island, Vanuatu

“…All participants in this study shared sleeping quarters with multiple children or adults. Higher numbers of co-sleepers might be expected to increase the number of nocturnal awakenings, and thereby reduce sleep efficiency and potentially sleep duration, as has been previously reported 30,34,40,41 . In the present study, the average number of co-sleepers was slightly greater in the non-electric communities (4.5 co-sleepers) compared to the electric communities (3.6 co-sleepers), yet the non-electric communities had both longer nocturnal sleep and higher sleep efficiency.…”

“…This study population provides some unique advantages, including homogeneity of ethnicity and lifestyle on the island, little seasonal variation in climate and daylength, and the availability of an electric grid in coastal but not inland villages, permitting a within-society comparison of sleep with and without access to on-demand electric lighting. Also, the latitude of Tanna Island, and thus the annual variation in photoperiod, is very close to the latitude of several hunter-gatherer societies previously shown to exhibit short sleep 27,30 , thus permitting cross-cultural comparisons with a natural control for daylength.…”

“…The findings generated from these studies have been variable. Daily sleep duration was observed to be unexpectedly short (~5 h–6.5 h group means) in traditional hunting and gathering societies in Africa and South America (the Hadza in Tanzania, the San in Namibia, and the Tsimane in Bolivia) 27,28 , an agrarian society in Madagasgar (the Malagasy) 29 , and a pastoralist society in Namibia (the Himba) 30 . By contrast, sleep duration was comparatively long in a traditional horticultural society of Papa New Guinea (~8.4 h) 31 , and in an Argentinian society (the Toba/Qom) who were traditionally hunter-gatherers (but are now mainly state supported 32 ) and showed a marked seasonal variation (~7 h in summer and 8.5 h in winter) 33 .…”

Biobehavioral variation in human water needs: How adaptations, early life environments, and the life course affect body water homeostasis

“…Sleep duration is an important health behavior with large interindividual variation, especially cross‐culturally. In the US, average adult sleep duration is slightly less than 7 hours with variation between and within groups, while Himba agropastoralist adults sleep less than 6 hours, and Italian adults report 8 hours (Prall, Yetish, Scelza, & Siegel, ). However, there's an increasing trend of short sleep in the US across all race/ethnicities, but this is an even bigger problem among non‐Hispanic black adults who more than 40% report sleeping 6 or fewer hours (Sheehan, Frochen, Walsemann, & Ailshire, ).…”

The ethics and logistics of field-based genetic paternity studies

“…However, the genetic component of this project is just one among many methods and topics the project is focused on. Using ethnographic, demographic and health data we have published studies addressing jealousy (Scelza, 2013b), partner choice , maternal and child health (Prall & Scelza, 2017;Scelza & Hinde, 2019), sleep (Prall, Yetish, Scelza, & Siegel, 2018), marriage and inheritance patterns (Scelza, The project is longitudinal in nature, and concentrates on 40-45 households, with whom we have regular contact. At least one member of the project goes to Namibia each year, along with a team of Namibian research assistants, many of whom have worked multiple field seasons.…”