Impact of sleep-wake features on fatigue among female shift work nurses

Figures & data

Table 1. Nurses’ demographic and working characteristics (N = 152).

Variable	Mean (SD)/N (%)	12h (n = 82)	8h (n = 70)	Comparison
		Mean (SD)/N (%)	Mean (SD)/N (%)	X^2/ t/Z	p Value
Age (years)	31.81 ± 6.09	31.81 ± 5.28	31.81 ± 6.97	−0.009	0.992
BMI	21.99 ± 3.29	22.05 ± 3.53	21.91 ± 3.01	0.249	0.804
Education level				6.928	0.074
Associate’s	30(19.7)	10(12.2)	20(28.6)
Bachelor’s and above	122(80.3)	70(87.8)	50(71.4)
Marital status				0.373	0.541
Married	93(61.2)	30(36.6)	41(58.6)
Single	59(38.8)	52(63.4)	29(41.4)
Years worked in the hospital^a	10(4, 16)	10(5, 15.25)	9.5(3, 16.25)	−0.248	0.804
Years worked in the ICU^a	7(2, 11.75)	4.5(2, 10)	8(3.00, 15.25)	−2.346	0.019
Nurse-patient ratio	3.85 ± 1.25	3.24 ± 0.95	4.56 ± 1.18	−7.441	0.000

^aAll are the median (P₂₅, P₇₅).

Table 2. Characteristics and differences in the sleep-wake index, reaction times, saliva cortisol level, and fatigue severity among 8- and 12-hour shifts nurses (N = 152).

	12h (n = 82)	8h (n = 70)	Comparison
Variable	Mean (SD)/N (%)	Mean (SD)/N (%)	X^2/ t/Z	p Value
Actigraphy
TST (min)	455.64 ± 97.30	363.98 ± 119.97	5.200	0.000
WASO (%)^a	3.86 (1.60, 7.23)	2.78 (1.30, 5.72)	−1.148	0.251
CAR	0.53 ± 0.13	0.50 ± 0.18	1.278	0.203
Salivary cortisol^a
Before day shift	0.535 (0.246, 1.045)	0.312 (0.152, 0.633)	−3.094	0.002
Abnormal	14 (17.1)	17 (24.3)
After day shift	0.202 (0.122, 0.456)	0.182 (0.072, 0.335)	−1.643	0.100
Abnormal	25 (30.5)	15 (21.4)
Before night shift	0.216 (0.123, 0.494)	0.194 (0.053, 0.463)	−1.697	0.090
Abnormal	29 (35.4)	19 (27.1)
After night shift	0.513 (0.262, 0.894)	0.313 (0.134, 0.619)	−2.778	0.005
Abnormal	10 (12.2)	16 (22.9)
Reaction time mean
Before day shift	321.55 ± 71.32	314.26 ± 72.54	0.623	0.534
After day shift	335.77 ± 88.09	310.30 ± 72.46	1.754	0.082
Before night shift	317.00 ± 76.04	303.34 ± 62.69	1.195	0.234
fter night shift	345.47 ± 93.63	357.03 ± 101.63	−0.729	0.467
Reaction time median
Before day shift	285.61 ± 57.37	277.04 ± 51.45	0.962	0.337
After day shift	303.25 ± 76.87	281.99 ± 60.42	1.872	0.063
Before night shift	288.46 ± 67.81	268.99 ± 36.42	2.150	0.033
After night shift	313.16 ± 74.23	308.51 ± 69.60	0.394	0.694
Fatigue severity
Before day shift	3.78 ± 2.26	4.76 ± 1.96	−2.816	0.006
After day shift	6.99 ± 2.13	5.99 ± 1.84	3.064	0.003
Before night shift	4.04 ± 2.55	6.42 ± 2.06	−6.267	0.000
After night shift	8.14 ± 1.88	7.62 ± 1.71	1.784	0.076

^aAll are the median (P₂₅, P₇₅).

TST: total sleep time; WASO: wake time after sleep onset; CAR: circadian activity rhythm.

Table 3. Differences in the two groups according to the median of CAR (N = 152).

Variable	Mean (SD)/N (%)	Mean (SD)/N (%)	X^2/ t/Z	p Value
12-hour (n = 82)	CAR ≤ 0.53 (n = 38)	CAR > 0.53 (n = 44)
Age (years)	33.55 ± 5.19	30.30 ± 4.92	2.914	0.005
Marital status			5.080	0.024
Married	29 (76.3)	23 (52.3)
Single	9 (23.7)	21 (47.7)
Years worked in the hospital^a	10 (5, 15.25)	9.5 (3, 16.25)	−2.436	0.015
TST (min)	427.76 ± 95.20	479.73 ± 93.57	−2.488	0.015
WASO (%)^a	6.47 (1.99,10.89)	2.85 (1.11, 5.48)	−3.050	0.002
Subjective fatigue
Before day shift	4.27 ± 2.27	3.36 ± 2.19	1.849	0.068
After day shift	7.41 ± 2.07	6.62 ± 2.11	1.712	0.091
Before night shift	3.98 ± 2.69	4.09 ± 2.45	−0.199	0.843
After night shift	8.30 ± 2.00	3.21 ± 0.93	0.713	0.478
8-hour (n = 70)	CAR ≤ 0.50 (n = 33)	CAR > 0.50 (n = 37)
Nurse-patient ratio	4.88 ± 1.11	4.27 ± 1.19	2.199	0.031
TST (min)	330.73 ± 134.48	393.65 ± 97.95	−2.254	0.027
Subjective fatigue
Before day shift	4.72 ± 2.06	4.79 ± 1.90	−0.153	0.879
After day shift	5.94 ± 2.17	6.03 ± 1.53	−0.204	0.839
Before night shift	6.01 ± 2.13	6.79 ± 1.94	−1.591	0.116
After night shift	7.41 ± 1.74	7.80 ± 1.69	−0.966	0.338

^aAll are the median (P₂₅, P₇₅).

TST: total sleep time; WASO: wake time after sleep onset; CAR: circadian activity rhythm.

Data availability statement

Data is available on request from the authors.