Subjective and objective sleep among air ambulance personnel

Figures & data

Table 1. Descriptive characteristics of sleep variables across three weeks during winter season and summer season

	Week before work		Workweek		Week after work
	Sleep diary	Actigraphy	Sleep diary	Actigraphy	Sleep diary	Actigraphy
Bedtime^a
Winter	24:06 (1:16)	24:11 (1:21)	24:33 (1:20)	24:54 (1:30)	24:18 (1:19)	24:28 (1:47)
Summer	24:14 (1:12)	24:28 (1:17)	24:54 (1:18)	01:13 (1:23)	24:22 (1:23)	24:33 (1:19)
Wake-up time^a
Winter	07:30 (1:16)	07:23 (1:23)	08:36 (1:26)	08:26 (1:25)	07:55 (1:26)	07:46 (1:30)
Summer	07:36 (1:21)	07:23 (1:25)	08:42 (1:34)	08:37 (1:37)	07:56 (1:25)	07:48 (1:23)
Time in bed^a
Winter	7:41 (1:13)	7:12 (1:21)	8:16 (1:28)	7:31 (1:30)	7:53 (1:14)	7:21 (1:22)
Summer	7:39 (1:22)	6:55 (1:12)	8:01 (1:38)	7:23 (1:34)	7:53 (1:23)	7:14 (1:17)
Wake after sleep onset^b
Winter	0:05 (0:00–0:15)	0:40 (0:29–0:55)	0:05 (0:00–0:30)	0:44 (0:30–1:15)	0:05 (0:00–0:15)	0:41 (0:28–1:01)
Summer	0:05 (0:00–0:11)	0:36 (0:26–0:48)	0:05 (0:00–0:20)	0:44 (0:28–1:16)	0:05 (0:00–0:15)	0:40 (0:28–0:56)
Sleep efficiency^b
Winter	92.5 (87.0–95.5)	86.6 (81.8–89.9)	92.5 (85.7–96.3)	84.4 (75.6–89.3)	93.0 (86.5–96.0)	85.5 (79.8–89.7)
Summer	93.4 (88.7–96.1)	87.4 (83.4–90.8)	91.9 (84.1–96.0)	85.4 (76.7–89.4)	93.7 (88.1–96.4)	86.2 (82.0–90.5)
Total sleep time^a
Winter	6:54 (1:17)	6:05 (1:22)	7:17 (1:26)	6:01 (1:24)	7:05 (1:17)	6:09 (1:23)
Summer	6:55 (1:21)	5:59 (1:12)	7:03 (1:30)	5:57 (1:27)	7:08 (1:33)	6:09 (1:16)

The sleep variables derive from sleep diary and actigraphy.

All sleep variables are presented in h:min format, except for sleep efficiency which is presented in percentages.

^aMean (SD)

^bMedian (quartiles)

Table 2. Estimates and standard scores for sleep variables between winter season and summer season workweek, and during the week before work, the workweek, and the week after work

	Workweeks		Three-week period
	Winter season	Summer season^ʃ	Week before work		Workweek^ʃ	Week after work
Sleep diary			Winter	Summer		Winter	Summer
Bedtime^a	−.359***		−.417***	−.676***		−.220*	−.569***
Wake-up time^a	−.089		−1.079***	−1.078***		−.663***	−.764***
Time in bed^a	.263*		−.588***	−.340**		−.393***	−.104
Wake after sleep onset^b	−.033		−4.039***	−3.469**		−3.704**	−3.747**
Sleep efficiency^b	−.722		−.524	−2.237		−1.680	−1.837
Total sleep time^a	.212		−.409***	−.132		−.229*	.080
Actigraphs
Bedtime^a	−.339**		−.694***	−.764***		−.483***	−.685***
Wake-up time^a	−.198		−1.027***	−1.220***		−.629***	−.859***
Time in bed^a	.134		−.327**	−.461***		−.163	−.164
Wake after sleep onset^b	−.477		−4.604***	−5.286***		−3.753**	−4.987***
Sleep efficiency^b	−.781		−3.069**	−4.769***		−2.947**	−4.968***
Total sleep time^a	.054		.069	.015		.141	.154

* p < 0.05, ** p < 0.01, *** p < 0.001

The sleep variables derive from sleep diary and actigraphy.

^aThe reported values are unstandardized b-scores from Linear Mixed Models.

^bThe reported values are z-scores from Mann Whitney U and Friedman ANOVA, post-hoc Wilcoxon. ^ʃ Represents the reference groups.

Figure 1. Mean scores of bedtime and wake-up time over three weeks during winter and summer season, measured by a) sleep diary and b) actigraphy. Error bars represent standard error