Fig. 1.

The total number of subjects who endorsed the five suicidal ideation symptoms over the last year (on the Paykel Scale) across the sleep duration categories. Item 1: Not worth living (past year), χ²=2.89, p=0.23; Item 2: Wished was dead (past year), χ²=2.06, p=0.35; Item 3: Taking own life (past year), χ²=2.12, p=0.34; Item 4: Thoughts/plans (past year), χ²= 7.70, p = 0.02; Item 5: Attempt (past year), χ² = 1.67, p = 0.43.

Sleep duration was assessed using the question, “How many hours of sleep did you usually get at night”, with the responses being recorded as hours a night. Short sleep duration (short sleep) was assessed as those reporting a habitual sleep duration of ≤6 hours a night; normal sleep duration (normal sleep) was assessed as those reporting sleeping 7–8 hours a night; long sleep duration (long sleep) was assessed as those reporting a nocturnal sleep duration of ≥9 hours.