Sleeping with elevated upper body does not ease acute mountain sickness

Sleeping with the upper body elevated by 30 degrees is not associated with relevant reductions in acute mountain sickness symptoms or hypoxaemia at high altitude, a recent study has shown.

The investigators of this pragmatic, randomized, observer-blinded field study at 4,554-m altitude examined 134 adults aged 18–70 years with a Lake Louise score between 3 and 12 points on the evening of their arrival at the high altitude to determine whether sleeping with an elevated upper body reduces the risk of acute mountain sickness.

Participants were exposed to sleeping on an inflatable cushion elevating the upper body by 30 degrees or on a sham pillow in a horizontal position. The primary endpoint was change in the Acute Mountain Sickness-Cerebral (AMS-C) score in the morning after sleeping at a high altitude compared with the evening before. The secondary endpoint was sleep efficiency.

Of the 219 eligible mountaineers, 134 met the inclusion criteria and were subsequently randomized to sleep on an inflatable cushion (intervention group) or on a sham pillow (control group).

The AMS-C score increased by 0.121±0.679 in the intervention group and by 0.250±0.575 in the control group (difference, 0.105, 95 percent CI, –0.098 to 0.308; p=0.308). Oxygen saturation in the morning was similar between the two groups at 79±6 percent and 78±6 percent (p=0.863), respectively. Moreover, no between-group difference was seen in sleep efficiency (p=0.115).

“Acute mountain sickness commonly occurs following ascent to high altitude and is aggravated following sleep. Cephalad fluid shifts have been implicated,” the investigators said.