Sleep profiles and mood state changes during an expedition to the South Pole: a case study of a female explorer.

Abstract

Objectives: To investigate sleep parameters and mood profiles of a female explorer traveling solo and unaided to the South Pole during the winter. Methods: During the 44-day expedition, global activity and sleep were assessed using a wrist actigraph (AW) worn on the non-dominant wrist. Mood was assessed using an adapted Profile of Mood States questionnaire. Pre- and post- expedition physiological profiles were conducted to assess body composition, strength and power and aerobic capacity. Results: The AW data revealed decreasing sleep duration throughout the expedition, with an average sleep time of 5 hours (range: 8hr 14mins – 1hr 42mins), with sleep times consistently below 3 hours during the final third of the expedition. Mood responses indicated a progressive reduction in vigour and increase in fatigue. Sleep time was positively related to vigour and inversely related to depression and fatigue, a finding that is consistent with the notion that positive feelings (high vigour and low fatigue) are linked with sleep. Conclusions: This account provides insight to help understand the limits of human tolerance and may be directly applicable when planning future expeditions of this nature.