Oxygen therapy lifted sleep and memory at high altitude

Living at high altitude means chronically thinner air, and poor sleep and blunted cognitive performance are recognised consequences for people who reside there long term. Enhancing the blood's oxygen-carrying capacity has been suggested as a therapeutic strategy for both problems, but good randomised evidence in healthy high-altitude residents has been lacking. This trial asked whether a short course of mild hyperbaric oxygen therapy (mHBOT) — breathing oxygen in a mildly pressurised chamber — could improve sleep quality and brain function in young adults living at very high altitude.

Sixty healthy young male participants who had resided at 4300 m for at least six months were randomly assigned 1:1 to a mild hyperbaric oxygen group or a control group for a 5-day intervention. The primary outcomes were sleep quality, measured with the Pittsburgh Sleep Quality Index, and brain function, assessed using functional near-infrared spectroscopy (fNIRS) — a non-invasive optical imaging method — recorded while participants performed a 2-back working-memory task. Cerebral functional connectivity was also analysed.

The mHBOT group achieved a significantly greater reduction in PSQI scores than controls (3.17 ± 2.69 versus 4.43 ± 3.39; adjusted mean difference -1.08, 95% CI -1.76 to -0.46, p = 0.003). They also recorded significantly higher accuracy on the working-memory task. The fNIRS data showed a significant decrease in oxygenated haemoglobin in the superior temporal gyrus (channels 18-22) during the task after treatment compared with baseline, which the authors interpret as altered activation patterns and reduced metabolic demand. Connectivity analysis additionally suggested enhanced network integration, which may indicate improved neurocognitive efficiency.

This supports the broader idea that oxygen availability is a limiting factor for sleep and cognition at altitude, and it extends hyperbaric oxygen research — more commonly studied in clinical rehabilitation — to healthy young residents of a high-altitude environment. The study is small, short and restricted to men, and the imaging outcomes are explicitly exploratory, so the mechanism claims should be treated as hypotheses. How long benefits last after the 5-day course ends, and whether they hold in women, older adults or visitors rather than long-term residents, are open questions.

For most readers at sea level, the direct relevance is limited, but the study is an interesting demonstration of how tightly sleep quality and working memory are tied to oxygen supply. If you live at, work at or trek to high altitude, it is a reason to take seriously the cognitive and sleep costs of chronic low oxygen — and to note that interventions targeting oxygen delivery are showing early promise. It is one small trial, not an established therapy.