Circadian Levels of Serum Melatonin and Cortisol in relation to Changes in Mood, Sleep, and Neurocognitive Performance, Spanning a Year of Residence in Antarctica

Table 5

Subjective assessment of sleep parameters during the summer and winter photoperiods in Antarctica.

	Summer	Winter	P value
Latency (min)	19.25 ± 9.35	16 ± 10.07	0.003
Duration (hrs)	8.1 ± 1.28	8.35 ± 1.03	0.204
Restorative sleep	11 (55%)	17 (85%)
Early awakenings	7 (35%)	6 (30%)
% reporting awakenings at night	8 (40%)	4 (20%)
Splitting sleep schedule	6/20 (30%)	2/20 (10%)
Subjective sleep quality; n (%)
(i) Good	11 (55%)	11 (55%)
(ii) Fair	5 (25%)	7 (35%)
(iii) Poor	4 (20%)	2 (10%)
Sleep aids n (%)	4/20 (25%)	6/20 (30%)
Caffeine intake (average number of cups/day)	2.6	2.7	0.329
Mean alcohol intake (g/week)	59.81 (𝑛=11)	88.5 (𝑛=12)	0.002