5.7-7.1 hours according to the study. They were in bed for 6.9-8.5 hours. * Sleep efficiency was between 81% and 86%, similar to that in industrial populatio

5.7-7.1 hours according to the study. They were in bed for 6.9-8.5 hours. * Sleep efficiency was between 81% and 86%, similar to that in industrial populations. * Naps longer than 15 minutes were uncommon, particularly in winter * sleep was generally initiated during a period of falling ambient temperature * Less than 3% reported sleep onset/offset problems occurring more than once a year Note the last point: although sleep duration may not be greater in hunter gatherers, there may be a difference in quality.