Biology subjects

Spiousas, I.

Publications and source records attributed to Spiousas, I..

4 recordsLinked to original sources

bioRxiv2026

Lunar gravity predicts sleep timing

Biological rhythms are fundamental to survival, synchronizing physiological and behavioural processes like the sleep-wake cycle with predictable environmental cycles like the solar day1. However, the extent to which human sleep responds to the lunar cycle remains a subject of controversy, particularly given the ubiquity of artificial light and conflicting reports regarding the influence of moonlight2-5. While lunar illuminance has been the primary candidate for such modulation, it fails to account for semilunar rhythms2,6 or effects observed during the dark new moon phase2,7. Here, we show that human and non-human primate sleep timing is synchronized with the gravimetric cycles exerted by the Moon and Sun. By analysing longitudinal actigraphic recordings from urban cohorts in Seattle, indigenous Toba/Qom communities in Argentina, and captive titi monkeys with attenuated access to natural light, we found that sleep onset is consistently delayed around periods of maximal gravitational variations. Crucially, this synchronization aligns with gravimetric peaks regardless of whether they occur at the full or new moon. Furthermore, while human sleep timing is heavily influenced by social constraints and self-selected light exposure, this synchronization persists in titi monkeys, in which these confounds are absent. These findings identify lunar gravity as a distinct environmental cue that may regulate sleep-wake behaviour. Although this regulation may be mediated by other geophysical factors oscillating with lunisolar gravitational tides, the results suggest that the mechanism is an evolutionarily conserved trait that shapes biological timing beyond the influence of light.

animal behavior and cognition↗

bioRxiv2025

Modern Times: Longitudinal Study of Toba/Qom Communities Reveals Delay and Shortening of Sleep in Real-Time Across Electrification

While artificial light and digital technologies are widely assumed to delay and curtail sleep, direct, longitudinal evidence documenting these changes is remarkably scarce. From 2012 to 2024, we conducted a longitudinal study of native Toba/Qom communities in northern Argentina, including rural groups newly introduced to electricity and semi-urban groups with earlier access to electricity. Using linear mixed-effects models on a dataset of over 12,000 actigraphically recorded sleep events from 156 participants at different times, we observed striking shifts in sleep dynamics. Remarkably, both groups showed delays of up to 1.4 hours in sleep timing, and participants from rural communities lost a full hour of sleep within just a decade. These changes occurred across a period that included, first, the introduction of electricity to rural communities after 2016, and, in more recent years, the spread of the internet and smartphone use among the Toba/Qom. Our models reveal that these events alone cannot fully explain the observed shifts in sleep timing, suggesting that broader processes of modernization and acculturation, beyond electric light and digital devices alone, may be driving sleep changes. The rapid transformations observed in these communities mirror, within a single decade, the likely trajectory of human sleep across the 20th and early 21st centuries, underscoring the complex ways modern environments reshape sleep behavior.

physiology↗

bioRxiv2023

Regulation of the circadian clock in C. elegans by clock gene homologs kin-20 and lin-42

Circadian rhythms are endogenous oscillations present in nearly all organisms from prokaryotes to humans, allowing them to adapt to cyclical environments close to 24 hours. Circadian rhythms are regulated by a central clock, which is based on a transcription-translation feedback loop. One important protein in the central loop in metazoan clocks is PERIOD, which is regulated in part by Casein kinase 1{varepsilon}/{delta} (CK1{varepsilon}/{delta}) phosphorylation. In the nematode Caenorhabditis elegans, period and casein kinase 1{varepsilon}/{delta} are conserved as lin-42 and kin-20, respectively. Here we studied the involvement of lin-42 and kin-20 in circadian rhythms of the adult nematode using a bioluminescence-based circadian transcriptional reporter. We show that mutations of lin-42 and kin-20 generate a significantly longer endogenous period, suggesting a role for both genes in the nematode circadian clock, as in other organisms. These phenotypes can be partially rescued by overexpression of either gene under their native promoter. Both proteins are expressed in neurons and seam cells, a population of epidermal stem cells in C. elegans that undergo multiple divisions during development. Depletion of LIN-42 and KIN-20 specifically in neuronal cells after development was sufficient to lengthen the period of oscillating sur-5 expression. Therefore, we conclude that LIN-42 and KIN-20 are critical regulators of the adult nematode circadian clock through neuronal cells.

neuroscience↗

bioRxiv2020

Moonstruck sleep: Synchronization of Human Sleep with the Moon Cycle under Natural Conditions

As humans transitioned from hunter-gatherer to agricultural to highly urbanized post-industrial communities they progressively created environments that isolated sleep from its ancestral regulators, including the natural light-dark cycle. A prominent feature of this isolation is the availability of artificial light during the night, which delays the onset of sleep and shortens its duration. Before artificial light, moonlight was the only source of natural light sufficient to stimulate activity during the night; still, evidence for the modulation of sleep timing by lunar phases under natural conditions is controversial. Here we use data collected with wrist actimeters that measure daily sleep to show a clear synchronization of nocturnal sleep timing with the lunar cycle in participants who live in environments that range from a rural setting without access to electricity to a highly urbanized post-industrial one. The onset of sleep is delayed and sleep duration shortened as much as 1.5 hours on nights that precede the full moon night. Our data suggests that moonlight may have exerted selective pressure for nocturnal activity and sleep inhibition and that access to artificial evening light may emulate the ancestral effect of early-night moonlight.

neuroscience↗