The effects of sleep medication on mountaineers

The prospect of a bad night in a high mountain refuge can be a source of anxiety for mountaineers who want to be on top form for the next day’s climb. With this in mind, some mountaineers might resort to sleeping pills. Although taking them can improve sleep quality, there are a number of risks associated with their residual effects, especially very early the morning after.

MAY 2018  •  Article updated in June 2019

Impact des somnifères sur les alpinistes

An information campaign will be launched on the risks associated with the use of sleep medication at high altitude. Information posters will be put up in refuges in the Alps from June 2019 (download the poster in A3)
  • Project partner: EXALT, Centre for Altitude Expertise (HP2 laboratory, Grenoble-Alpes University and Grenoble-Alpes University Hospital)
  • Country: France
  • Project type: Gaining knowledge
  • Budget: €12,000 since 2016

A team of researchers from HP2 laboratory, Grenoble Alpes University has studied the impact of sleep medication on the vigilance and motor agility of mountaineers when awoken in the middle of the night at high altitude. The results highlight a reduction in physical and mental ability that could potentially increase the risk of accidents.

The residual effects of sleeping pills early in the morning impair alertness and motor skill, exposing mountaineers to an increased risk of accidents.

A study on the effects of sleeping pills among mountaineers (see below) was published in 2018 by members of the EXALT association. It showed that at high altitude, when taken just before sleeping, this medication causes a residual effect when mountaineers start their ascent after less than 5 hours’ sleep. This effect may result in reduced alertness and motor skill, which are detrimental to their safety. Before being tempted to take sleep medication, a mountaineer should bear in mind that physical activity is a powerful physiological activator that counteracts the potentially deleterious effects of poor sleep quality the previous night. It is therefore recommended to sleep well during the nights preceding a high altitude stay, and to use short naps as effective recovery opportunities outside the usual night time sleep.

This new knowledge deserved wider circulation among all mountaineers, be they amateur or professional. On June 14, 2019, the EXALT association, the French Alpine Club, the National School of Skiing and Mountaineering and the Petzl Foundation launched an information campaign on the risks associated with the use of sleep medication at high altitude. Information posters will be put up in refuges in the Alps from June 2019.

Demonstration of the effects of sleep medications

Impact des somnifères sur les alpinistes

In July 2017, researchers from the EXALT association recruited 22 subjects to conduct physical and cognitive tests. These tests were performed first at low altitude, in Grenoble, and later at the Aiguille du Midi, at 3,800 m, to assess the effects of sleep medication at high altitude. After ingesting a sleeping pill or a placebo, the subjects slept for four hours. They were then awoken at 1:30 am and subjected to a battery of tests under medical supervision.

The results highlighted that taking 10mg of Zolpidem (sleep medication) at bed time altered a mountaineer’s balance four hours later to an extent liable to impact their abilities and safety.

In addition, it was demonstrated that taking a sleeping pill increases reaction times and the number of errors made in simple cognitive tests. It appears that the alteration of cognitive performance is linked to an overall alteration of brain function. The results suggest that taking sleep medication in the evening before waking up in the middle of the night may increase the risk of accidents.

Self-medication among mountaineers

Arrivée au refuge du Goûter
The Goûter refuge, on the normal route of Mont Blanc

In order to investigate self-medication among mountaineers, a group of altitude experts (doctors, researchers, mountaineers) joined forces within the Center for Altitude Expertise (EXALT). In 2013, an initial study conducted at the Cosmiques and Goûter mountain refuges, at the foot of the normal routes up Mont Blanc, indicated that the mountaineering community consumes significant quantities of medication. Around 39% of the 430 samples collected revealed that medication had been taken, primarily diuretics to combat altitude sickness (acetazolamide or “Diamox”, 20.6%) and sleeping pills (12.9%). The results of the study, published in 2016, confirmed that the use of sleeping pills is common practice among mountaineers.

See the results of the study, published in June 2016 by the American peer reviewed journal PLOS

Not only did this first study raise awareness of this issue and its impact on the safety of mountaineers, it also prompted researchers to further explore the effects of the use of sleeping pills at high altitude.

To know more about EXALT and the studies conducted by the association

Samuel Vergès, Centre for Altitude Expertise:

Samuel Vergès

“Along the normal routes of Mont Blanc, a sleeping pill taken in the evening may still have an effect when the mountaineers begins his/her ascent, due to the early hour of departure. Our team therefore tested the effects on functional capacities of a sleeping tablet taken at bed time in the event of an early rise. Our research indicates that such taking such a drug has a substantial effect on the balance and cognitive functions liable to alter the abilities and safety of a climber equipped with crampons and holding ice axes, in a demanding environment.”

Uploaded in June 2019


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