**8. Conclusions**

measured by sleep log question [59, 60] and PSQI (4.15 2.76 in zolpidem group

*Summary of non-benzodiazepines in improving sleep architecture at high altitude. Modified from*

Benzodiazepine use in this environment is controversial. Early studies showed that 1 mg of oral loprazolam did not worsen either slow wave sleep depression or apnea and allowed normal sleep reappearance after acclimatization [28, 62]. Later, a randomized, double-blind, placebo-controlled trial conducted at 3000 m altitude validated PaO2 decreasing and PaCO2 increasing significantly 1 hour after 5 mg of

On the contrary, temazepam, a short-acting benzodiazepine, was recommended to be safely used by the International Climbing and Mountaineering Federation MedCom Consensus Guide [51]. However, the effect of temazepam on the objective sleep parameters was inconsistent. Nicholson et al. [64] reported that temazepam significantly shortened the mean sleep onset latency and increased the amount of the REM sleep, whereas Nickol et al. [65] reported no differences in the actigraphyderived sleep parameters. Results on oxygen saturation and PB from the aforementioned studies were also inconsistent. When compared to the placebo, temazepam showed no significant effect on mean oxygen saturation, yet PB significantly decreased [66]. Although Nickol et al. [65] reported that temazepam could decrease

oral diazepam [63], which suggests that it may cause hypoventilation.

vs. 6.58 3.98 in placebo group, P = 0.047) [60].

*Updates in Sleep Neurology and Obstructive Sleep Apnea*

*7.3.3 Benzodiazepines*

**Figure 6.**

**118**

*Kong et al. [61].*

Our understanding on sleep disorder at high altitude is still limited. Mountain tourists commonly complain about subjective sleep disturbances with difficulty in onset of sleep and frequent awakenings in the first few nights at altitude. But those subjective sensations of poor sleep neither are associated with severity of mountain sickness nor tend to disappear after long exposure to high altitude. And consequently, cognitive function was impaired.

There is no reliable evidence that support the consistency between self-report sleep quality and sleep parameters obtained from PSG. The most frequently reported changes in sleep architecture at high altitude are detected by PSG including a decrease in NREM sleep and occurrence of PB. Different patterns of adoption to hypoxic environment exist among native highlanders. For lowlanders ascending to high altitude, acclimatization would be beneficial in relieving hypoxemia and improving deep sleep; however, PB would not be largely relieved after acclimatization.

The occurrence of HASD is prior to most altitude-related diseases and would last for a longer time. We strongly suggest future study to consider it as an independent high-altitude illness as it had been removed from the diagnosing and managing of AMS by the International Society of Mountain Medicine World Congress Committee.

The treatment principle of HASD should not deteriorate nocturnal ventilation and SaO2 or affect sleep architecture. The following evidence-based choices are recommended. Effective treatments for altitude-related nocturnal hypoxemia include dietary NO3 supplementation before sleep and supplemental oxygen during sleep. Medication for respiratory disturbance is 250 mg daily dose of oral acetazolamide, which is beneficial in relieving sleep apnea, decreasing AHI and PB, and promoting nocturnal oxygenation. Both zaleplon and zolpidem are optional agents in improving the objective sleep architecture and subjective sleep quality without impairing ventilation.

*Updates in Sleep Neurology and Obstructive Sleep Apnea*

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