Moonstruck sleep: Synchronization of human sleep with the moon cycle under field conditions

Before the availability of artificial light, moonlight was the only source of light sufficient to stimulate nighttime activity; still, evidence for the modulation of sleep timing by lunar phases is controversial. Here, we use wrist actimetry to show a clear synchronization of nocturnal sleep timing with the lunar cycle in participants living in environments that range from a rural setting with and without access to electricity in indigenous Toba/Qom communities in Argentina to a highly urbanized postindustrial setting in the United States. Our results show that sleep starts later and is shorter on the nights before the full moon when moonlight is available during the hours following dusk. Our data suggest that moonlight likely stimulated nocturnal activity and inhibited sleep in preindustrial communities and that access to artificial light may emulate the ancestral effect of early-night moonlight.Fil: Casiraghi, Leandro Pablo. University of Washington; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Spiousas, Ignacio. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnologia. Laboratorio de Dinamica Sensomotora.; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Dunster, Gideon P. University of Washington; Estados UnidosFil: McGlothlen, Kaitlyn. University of Washington; Estados UnidosFil: Fernandez Duque, Eduardo. University of Yale; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Valeggia, Claudia Rita. University of Yale; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: de la Iglesia, Horacio Oscar. University of Washington; Estados Unido