Prolonged isolation and the polar night independently influence autonomic regulation, with increasing isolation associated with decreased parasympathetic activity during wakefulness and increased parasympathetic activity during sleep, while the polar night was associated with decreased parasympathetic activity during sleep.
Parasympathetic regulation during wakefulness decreased in association with increasing duration of isolation during an Antarctic overwintering.
Parasympathetic regulation during sleep increased in association with increasing duration of isolation.
Parasympathetic activity during sleep decreased during the polar night, suggesting a distinct seasonal effect separate from isolation duration.
The study identified both isolation-related and seasonal (polar night) influences on autonomic nervous system activity in an Antarctic overwintering population.
The study demonstrates that the sleep-wake cycle provides a meaningful framework for detecting differential autonomic adaptations to extreme environment stressors.
This research followed 13 people stationed at a remote Argentine Antarctic base over the course of a full year. Every two months, the researchers measured heart rate variability (HRV) — a way of assessing how well the body's automatic nervous system is functioning — over full 24-hour periods. By separating readings taken during sleep from those taken while awake, they could see how the body's self-regulation changed in two different states across the year. The study found two distinct patterns. First, as the time spent in isolation grew longer, people's 'rest-and-digest' (parasympathetic) nervous system became less active while they were awake, but more active while they were asleep. This suggests the body may be gradually shifting its recovery processes more heavily into sleep as isolation stress accumulates. Second, during the polar night — the months of extended darkness unique to Antarctica — parasympathetic activity during sleep actually decreased, pointing to a separate seasonal effect driven by the absence of sunlight rather than isolation alone. This research suggests that living in extreme, isolated environments like Antarctic stations affects the body's automatic regulation systems in ways that differ depending on both how long someone has been isolated and what season it is. These findings could be relevant for designing health-support strategies for people in similar conditions, such as long-duration space missions or remote postings, where both prolonged confinement and disrupted light cycles are unavoidable.
Tortello C, Folgueira A, Cauda B, González L, Sala Lozano E, Pattyn N, et al.. (2026). Autonomic regulation across sleep and wake during an Antarctic overwintering.. Scientific reports. https://doi.org/10.1038/s41598-025-31009-x