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Sleep profiles and mood states during an expedition to the South Pole
Charles R Pedlar1, Andrew M Lane, Juliette C Lloyd
1English Institute of Sport, St Mary's College, Twickenham, UK. Charles.Pedlar@eis2win.co.uk
Objective:
To study 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 nondominant wrist. Mood was assessed using an adapted Profile of Mood States questionnaire. Pre- and post expedition physiologic 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, 8 hours and 14 minutes to 1 hour and 42 minutes), with sleep times consistently <3 hours during the final third of the expedition. Mood responses indicated a progressive reduction in vigor and increase in fatigue. Sleep time was positively related to vigor and inversely related to depression and fatigue, a finding that is consistent with the notion that positive feelings (high vigor 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.
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