Table 2.

Sleep Time Depending on Shift Type and Time of Day.

		Night 9 pm–9 am			Day 9 am–9 pm			Night + Day (9 pm–9 pm)
	Nights (N)	Shift type	Sleep time hours (95% CI)	p	Shift type	Sleep time hours (95% CI)	p	Sleep time hours (95% CI)	p
InternsHUP & VA	1731	Before regular shift	6.93 (6.83;7.03)	Ref.	On regular shift	0.18 (0.12;0.25)	Ref.	7.11 (7.00;7.22)	Ref.
	1118	Before call	7.12 (7.01;7.22)	<.001	On-call	0.02 (0.00; 0.09)	<.001	7.14 (7.02;7.26)	.60
	1088	On-call	2.19 (2.08;2.29)	<.001	Post call	3.26 (3.19; 3.33)	<.001	5.45 (5.33;5.57)	<.001
	513	Before day off	8.07 (7.94;8.20)	<.001	On day off	0.98 (0.89;1.08)	<.001	9.05 (8.91;9.20)	<.001
	4450	All shift types	5.95 (5.86;6.03)	—	All shift types	0.99 (0.94;1.04)	—	6.93 (6.84;7.03)	—
ResidentsHUP	434	Before shift 7 am–5 pm	6.75 (6.62;6.89)	Ref.	On shift 7 am–5 pm	0.05 (0.01;0.08)	Ref.	6.80 (6.67;6.94)	Ref.
	524	Before Shift 7 am–8 pm	7.00 (6.87;7.13)	<.001	On shift 7 am–8 pm	0.03 (0.00;0.07)	.569	7.03 (6.90;7.16)	<.001
	103	Before day off	8.29 (8.11;8.48)	<.001	On day off	1.25 (1.17;1.32)	<.001	9.55 (9.34;9.75)	<.001
	1061	All shift types	7.02 (6.90;7.14)	—	All shift types	0.15 (0.12;0.18)	—	7.18 (7.06;7.30)	—
ResidentsVA	649	Before shift 8 am–5 pm	6.80 (6.62;6.98)	Ref.	On shift 8 am–5 pm	0.18 (0.11;0.26)	Ref.	6.99 (6.80;7.18)	Ref.
	214	Before shift 8 am–8 pm	7.22 (7.01;7.44)	<.001	On shift 8 am–8 pm	0.02 (0.00;0.12)	.002	7.24 (7.01;7.48)	.015
	31	Before Sat 8 am–1 pm	6.17 (5.75;6.59)	.002	On Sat 8 am–1 pm	0.13 (0.00;0.37)	.67	6.31 (5.82;6.80)	.005
	67	Before call	7.10 (6.79;7.40)	.037	On-call	0.06 (0.00;0.23)	.144	7.16 (6.81;7.51)	.31
	65	On-call	3.16 (2.85;3.47)	<.001	Post call	3.47 (3.30;3.63)	<.001	6.63 (6.27;6.98)	.033
	100	Before day off	8.22 (7.95;8.49)	<.001	On day off	1.00 (0.86;1.13)	<.001	9.22 (8.92;9.52)	<.001
	1126	All shift types	6.81 (6.63;6.98)	—	All shift types	0.40 (0.34;0.47)	—	7.21 (7.03;7.38)	—

CI = Confidence Interval; Ref. = Reference Category; Sat = Saturday.