多相睡眠
↑ Capellini, I.; Nunn, C.L.; McNamara, P.; Preston, B.T.; Barton, R.A. 2008. Energetic constraints, not predation, influence the evolution of sleep patterning in mammals. Functional Ecology 22:847–853.
↑ http://www.historycooperative.org/journals/ahr/106.2/ah000343.html, Sleep We Have Lost: Pre-industrial Slumber in the British Isles, The American Historical Review
↑ ジェッサ・ギャンブル 「自然な睡眠周期」の講演映像 - TEDカンファレンス、2010年9月、4分1秒。
↑ Wehr, T.A. (June 1992). “In short photoperiods, human sleep is biphasic”. J Sleep Res 1 (2): 103–107. doi:10.1111/j.1365-2869.1992.tb00019.x. PMID 10607034.
↑ Coturnix (16 October 2006). “What is a 'natural' sleep pattern?”. A Blog Around the Clock (ScienceBlogs). http://scienceblogs.