Sleep quality changes in insomniacs and non-insomniacs after acute altitude exposure and its relationship with acute mountain sickness

Figures & data

Table 1 Demographic characteristics of the participants

	Insomnia group (n=81)	Non-insomnia group (n=305)	P-value
Age, years	25.28±4.82	23.17±4.21	<0.001
Weight, kg	64.45±8.38	64.37±7.41	>0.05
BMI, kg/m^2	22.52±2.81	21.91 ±2.19	>0.05
Smoking, yes	50 (61.73)	168 (55.08)	>0.05
Drinking, yes	11 (13.58)	36 (11.80)	>0.05
Race			>0.05
Chinese Han	71 (87.65)	262 (85.90)
Others	10 (12.35)	43 (14.10)
Education			>0.05
Junior school	22 (27.16)	76 (24.92)
High school	36 (44.44)	149 (48.85)
College	23 (28.40)	80 (26.23)

Note: Data are shown as the mean ± standard deviation or n (%).

Abbreviation: BMI, body mass index.

Figure 1 Changes in the Athens Insomnia Scale¹³ score (A) and prevalence of insomnia (B) among insomniacs and non-insomniacs after arrival at high altitude.

Notes: Compared to the values obtained at 500 m in the same group: *P<0.05, **P<0.01, ***P<0.001.

Figure 2 Changes in the prevalence of insomnia symptoms (Athens Insomnia Scale¹³ items) among insomniacs and non-insomniacs after arrival at high altitude.

Notes: (A) Difficulty in sleep induction; (B) arousal during the night; (C) awakening in the early morning; (D) shortened total sleep duration; (E) decreased total sleep quality; (F) decreased sense of well-being in the daytime; (G) decreased functioning in the daytime; (H) daytime sleepiness. Compared to the values obtained at 500 m in the same group: *P<0.05, **P<0.01, ***P<0.001.

Figure 3 Comparisons of Lake Louise score⁴ (A) and the prevalence of AMS (B) between the insomnia and non-insomnia groups at 3,700 m.

Notes: P-values are indicated as: *P<0.05, **P<0.01, ***P<0.001.
Abbreviation: AMS, acute mountain sickness.

Figure 4 Comparisons of the prevalence of acute mountain sickness symptoms.

Notes: (A) Headache; (B) dizziness/lightheadedness; (C) insomnia; (D) fatigue/weakness; (E) gastrointestinal distress. Comparisons were performed with chi-squared tests: *P<0.05, **P<0.01, ***P<0.001.

Table 2 Physiological parameters between the insomnia and non-insomnia groups

	500 m	3,700 m
		1 day	3 days	7 days	14 days	60 days
HR, bpm
Insomnia group	65.77±8.98	87.22±12.57*	86.29±10.34*	84.81±10.03*	82.11±9.45*	80.15±9.75*
Non-insomnia group	66.50±8.76	84.28±12.80*,#	83.07±10.11*,#	82.69±9.72*	80.85±9.33*	79.47±10.63*
SaO2, %
Insomnia group	97.96±0.99	88.37±3.18*	88.75±3.44*	89.58±3.45*	90.33±3.77*	90.74±3.32*
Non-insomnia group	98.07±0.95	89.32±3.11*	90.30±3.59*	90.83±3.53*	90.95±3.50*	91.21±3.58*

Notes: Data are shown as the mean ± standard deviation. ANOVA for repeated measures, compared to the values obtained at 500 m within group:

* P<0.001; compared to the values of the insomnia group on the same day:

# P<0.05.

Abbreviations: ANOVA, analysis of variance; HR, heart rate; SaO₂, arterial oxygen saturation.

Table 3 Multivariate logistic regression analysis of the risk factors for acute mountain sickness

	β	SE	Wald	P-value	OR (95% CI)
AISSs^Citation13	0.336	0.020	227.481	<0.001	1.388 (1.314–1.464)
SaO2	−0.057	0.018	7.476	<0.01	0.931 (0.894–0.971)
Duration of altitude exposure	−1.232	0.131	98.105	<0.001	0.296 (0.227–0.378)

Note: Dependent variable: acute mountain sickness.

Abbreviations: AISS, Athens Insomnia Scale score; CI, confidence interval; OR, odds ratio; SaO₂, arterial oxygen saturation; SE, standard error.

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