Table 5.

Total 24-Hour Sleep Duration and Risk of Mortality, Stratified on Daily Napping

Type of Death	Total 24-Hour Sleep Duration (hours)	Hazard Ratio (95% Confidence Interval)*compared to 8 to < 9 hours 24-hour sleep duration (referent group)
		Overall Cohort	Did Not Nap Daily	Napped Daily	p- value†
All-cause	< 6	0.95 (0.76–1.18)	0.90 (0.71–1.14)	2.03 (0.93–4.42)	.08
	6 to < 8	1.07 (0.94–1.22)	1.03 (0.90–1.19)	1.58 (1.01–2.46)	.06
	9 to <10	1.28 (1.08–1.52)	1.17 (0.96–1.43)	1.46 (0.97–2.21)	.24
	≥ 10	1.58 (1.27–1.95)	1.51 (1.15–1.99)	1.58 (1.02–2.44)	.83
Cause-specific
Cardiovascular	< 6	0.90 (0.63–1.29)	0.85 (0.59–1.24)	1.75 (0.39–7.89)	.49
	6 to < 8	1.05 (0.84–1.30)	0.98 (0.78–1.22)	1.98 (0.97–4.02)	.04
	9 to <10	1.52 (1.16–2.00)	1.31 (0.96–1.80)	1.95 (1.01–3.77)	.12
	≥ 10	1.77 (1.28–2.45)	1.52 (0.99–2.33)	2.36 (1.20–4.66)	.35
Other	< 6	0.81 (0.54–1.21)	0.72 (0.47–1.11)	2.64 (0.84–8.26)	.04
	6 to < 8	1.16 (0.94–1.44)	1.09 (0.87–1.37)	2.20 (1.08–4.46)	.03
	9 to <10	1.34 (1.00–1.79)	1.19 (0.86–1.66)	1.61 (0.81–3.21)	.30
	≥ 10	1.71 (1.22–2.41)	1.69 (1.09–2.63)	1.64 (0.80–3.39)	.87

^*Adjusted for age; body mass index; history of at least one medical condition including diabetes mellitus, Parkinson’s disease, dementia, chronic obstructive pulmonary disease, non-skin cancer, and osteoarthritis; history of cardiovascular disease; history of hypertension; walks for exercise; alcohol use; smoking status; depression; cognitive impairment; estrogen use; and benzodiazepine use.

^†p-value for daily napping * total 24-hour sleep duration interaction.