About This Project

Moonlight represents a source of natural light that likely modulated sleep in ancestral human communities. Our preliminary data from traditionally hunter-gatherer Toba/Qom communities from Argentina without access to electricity suggest that sleep is disrupted during moonlit nights. We would like to quantitatively determine whether sleep timing and consolidation is associated with moon phases by measuring the sleep-wake cycle timing in these communities with wrist activity monitors .

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What is the context of this research?

Before we had access to inexpensive sources of artificial light, light hours were limited to the daytime, and to nights with bright enough moonlight to allow nocturnal activity. I have access to two Toba/Qom communities of similar sociocultural and genetic background, but only one has access to electricity. These communities represent a unique opportunity to study traditional human societies in a non-invasive way to address a fundamental question: How was human ancestral sleep modulated by the moon cycle? Although laboratory studies suggest that the moon cycle may modulate the quality of sleep (http://www.ncbi.nlm.nih.gov/pu...) no field studies have been done in human communities, let alone in communities without electric light, where moonlight is likely a salient stimulus.

What is the significance of this project?

We have demonstrated that access to electricity is associated with a later sleep onset and shorter daily sleep duration (http://www.ncbi.nlm.nih.gov/pu..., http://www.ncbi.nlm.nih.gov/pu...). These studies have demonstrated that in the absence of electric light, natural daylight is a prominent regulator of sleep timing. Our hypothesis is that in the absence of artificial light moonlight represents a salient stimulus that regulates sleep timing and quality. We seek to test the prediction that during moonlit nights sleep will be disrupted in communities without access to electricity. This would represent the first field demonstration that sleep is associated with moonlight and would suggest that the moon cycle was likely a prominent regulator of sleep in our human ancestors.

What are the goals of the project?

We will test the prediction that sleep during moonlit nights in participants of the Toba/Qom community without electricity will be fragmented compared to sleep in the same individuals during nights without moonlight. We will quantitatively measure the sleep-wake cycle with wrist activity monitors in several participants throughout two new and two full moons and assess the association between sleep parameters and lunar phases or moonlight intensity. We will simultaneously study participants with access to electricity and test the prediction that in this community the effects of moon phase or moonlight on sleep will be less prominent than in the community without electricity.