Table 2. Overall prevalence (%) of AMS-associated symptoms on different days^c.

	Headache	Dizziness	Fatigue	GI symptoms	Sleep disturbance b
Day 1 a	14.7	14.2	11.2	3.6	N/A
Day 2 a	46.2*	40.6¶	27.9	12.7	57.9*
Day 3 a	31.3	41.7¶	32.3*	22.4*	49.5
Overall	58.4	61.9	45.7	28.9	74.6

Abbreviations: AMS, acute mountain sickness; GI symptoms, gastrointestinal symptoms.

^a Day 1: Qika Hut, 2,460 m. Day 2: Sanliujiu Hut, 3,100 m. Day 3: Sanliujiu Hut, after reaching the summit of Xue Mountain (3,886 m).

^b The sleep disturbance score reflected the sleep quality during the night before evaluation, but the sleep disturbance score of Day 1 is not taken into account because all subjects slept at home (near sea level) on the night before trekking.

^c McNemar’s test was used to determine the difference in prevalence of each symptom from day to day.

^¶ p < 0.05 indicates that the prevalence of dizziness was higher on Day 2 and Day 3 compared with Day 1. However, there was no significant difference between Day 2 and Day 3.

* p < 0.05 indicates a statistically higher prevalence compared with other days.