How High Should You Sleep?

2,000 m, 2,500 m, 3,000 m or 3,500 m? For athletes using a simulated-altitude tent or room, the highest setting isn't automatically the right one. Research into normobaric hypoxia—the reduced-oxygen environments used in many simulated-altitude systems—has investigated all these levels, but with different exposure hours, athletes and outcomes.

Key takeaway: There is no universally validated optimal simulated sleeping altitude. The setting, hours per night, total days, and individual response all matter. The studies below should not be used as guarantees of results from any specific device.

A practical comparison of altitude ranges

These are convenient categories for comparing studies, not validated physiological training zones or personalised prescriptions.

Lower simulated altitude: 2,000–2,400 m

Czuba et al. (2018): 2,100 m

A study of 30 competitive off-road cyclists compared training approaches. One group of ten spent approximately 11–12 hours daily during evenings and nights at simulated 2,100 m for three training weeks while training in normal air. The researchers reported an approximately 4.8% rise in VO₂max and 3.6% improvement in a simulated 30 km cycling time trial for the hypoxic group. Caveat: the intervention involved more than eight hours nightly, only ten cyclists received it, and results do not establish a universal overnight dose.

Czuba et al. (2018) — original study

Saugy et al. (2014): 2,250 m

In a study of 27 well-trained triathletes, 14 athletes accumulated approximately 220 hours over 18 days in normobaric hypoxia at 2,250 m, while 13 used a natural-altitude comparison condition. Within the simulated group, researchers reported an increase of approximately 6.1% in VO₂max; immediate 3 km performance did not significantly improve. Caveat: this was a longer daily exposure programme, not a test of eight-hour sleep alone or comparison with sea-level control.

Saugy et al. (2014) — original study

Moderate simulated altitude: 2,500–2,900 m

Kinsman et al. (2005): 2,650 m

Fourteen endurance-trained men underwent protocols involving 15 overnight exposure nights at simulated 2,650 m, comparing consecutive nights with divided blocks. The study examined sleep-related physiological responses, not subsequent race performance. Caveat: it cannot establish that 2,650 m is an optimal training elevation.

Kinsman et al. (2005) — original study

Brocherie et al. (2015): approximately 2,800–3,000 m

In a controlled study involving elite male team-sport athletes, two simulated-altitude groups spent at least 14 hours per day over 14 days at approximately 2,800–3,000 m, alongside different sprint-training conditions. The investigators reported increases in selected intermittent running outcomes relative to the training programme comparison. Caveat: training conditions were part of the intervention and exposure was far longer than an ordinary eight-hour night; the study did not isolate the ideal sleeping setpoint.

Brocherie et al. (2015) — original study

Higher simulated altitude: 3,000–3,500 m

Ashenden et al. (1999): 3,000 m

Six male endurance athletes slept for 8–10 hours per night at simulated 3,000 m for 23 nights, with seven controls sleeping near sea level. Caveat: this was a small study of one specific outcome, so it says little about other 3,000 m programmes.

Ashenden et al. (1999) — original study

Neya et al. (2007): 3,000 m

In a study of 25 collegiate runners, an overnight simulated-altitude group spent around 11 hours nightly for 29 nights at approximately 3,000 m while training near sea level. The researchers reported an improvement of approximately 5% in running economy at race speed, but not significant improvements in VO₂max or treadmill time to exhaustion. Caveat: a 5% change in running economy is not a 5% improvement in race time.

Neya et al. (2007) — original study

Bejder et al. (2017): progressing to 3,500 m

Seven highly trained triathletes completed a double-blind, placebo-controlled crossover protocol of eight hours per day over six weeks: two weeks each at simulated 2,500 m, 3,000 m and 3,500 m. The researchers did not detect significant improvements in their tested cycling performance outcomes versus placebo. Caveat: the sample was small and the altitudes were sequential, so this does not independently compare each elevation.

Bejder et al. (2017) — original study

What about progressing gradually?

Saunders et al. (2004): 2,000–3,100 m

Elite distance runners followed 20 nights of simulated hypoxia across four weeks, spending 9–12 hours per exposure night in a chamber with the setting progressively increasing from about 2,000 m to 3,100 m. The study reported a 3.3% improvement in running economy compared with comparison groups. Caveat: it did not establish which altitude contributed most, nor directly demonstrate an equivalent race-time improvement.

Saunders et al. (2004) — original study

Hinckson and Hopkins (2005): 2,500–3,500 m

Eleven male sub-elite runners and triathletes completed a crossover investigation with an average 8.1 hours per day of tent exposure over about 25 days, progressing from 2,500 m toward 3,500 m. Treadmill data generated estimated race-time improvements at 800 m, 1,500 m and 3,000 m. Caveat: these were modelled estimates, not observed competition results, and the study could not determine which setting mattered most.

Hinckson and Hopkins (2005) — original study

Exposure hours matter as much as metres

At the same setting, eight hours each night for 28 nights is 224 hours; fourteen hours per day for 28 days is 392 hours. These are substantially different exposure programmes. The Gore et al. (2013) meta-analysis pooled results across altitude protocols, but its population-average estimates should not be applied as a guaranteed formula for an individual using overnight-only hypoxia.

Track the altitude, nightly hours and total days together rather than treating altitude alone as the effective dose.

Overnight SpO₂ from your ring or watch

Many rings and watches record SpO₂ overnight, although wrist-based readings vary in quality and do not replace a clinical-grade assessment.

Readings somewhere around 87–95% may be encountered under simulated hypoxia, but 87–95% is not an evidence-based target, and 88% should never be presented as a value athletes ought to aim for. The smartwatch reading in this article's illustration is an example, not a recommendation. Hoshikawa et al. (2007) reported an average overnight saturation around 89.6% during a one-night simulated 2,000 m exposure in eight male athletes; this study also documented sleep-related disturbances and did not test performance.

Hoshikawa et al. (2007) — original study

Useful context includes an individual's normal-air baseline, altitude setting, average and time course of nightly saturation, resting/overnight heart rate, HRV and previous altitude exposure. A lower reading is not a goal. Seek professional advice if you have symptoms.

Does a higher VO₂max mean you can sleep higher?

VO₂max measures maximal oxygen uptake during intense exercise. It is relevant context about aerobic capacity, but it is not a validated predictor of how high someone can comfortably or appropriately sleep in simulated hypoxia. Overnight oxygenation and breathing control are distinct from maximal exercise oxygen uptake.

For example, Faiss et al. (2014) studied elite and recreational ski mountaineers during exercise at simulated 3,000 m and found different relative changes in VO₂max and oxygen saturation between groups. Caveat: that exercise study did not test overnight tolerance and cannot justify setting sleeping altitude from an athlete's VO₂max.

The practical approach is to consider fitness alongside previous exposure, wearable trends, training conditions and individual tolerance—not to use a VO₂max-to-altitude conversion.

Faiss et al. (2014) — research article

Using Box Altitude and Oxygen Coach to follow your response

The Box Altitude bedroom systems and Sleep Cloud create controlled simulated-altitude environments. Their environmental oxygen readings describe what the equipment delivers; wearable SpO₂ is overnight data from your ring or watch. The two should not be confused.

Oxygen Coach helps bring recorded natural and simulated altitude exposure together with authorised wearable and training data, making it easier to look at altitude settings, accumulated hours and personal trends. Supported integrations and which SpO₂ measurements are available depend on the device, permissions and app version.

Comparing exposure logs with available SpO₂, heart-rate and other measurements can help an athlete and coach review a programme. It cannot prove that someone is “high enough” or guarantee performance improvements. Wrist oxygen readings can have meaningful errors in hypoxia.

Related reading: What Altitude Should You Sleep At? A Practical Guide and Altitude Training for Cyclists.

Frequently asked questions

Is 2,000 m too low?

Not necessarily. Czuba et al. (2018) observed changes at simulated 2,100 m with 11–12 hours of exposure daily. That does not establish benefits from eight-hour-only nights.

Is 3,000 m better than 2,500 m?

Not inherently. Direct comparisons designed to isolate those exact overnight settings are limited, and studies at 3,000 m have reported both positive and null findings across different outcomes.

Should I try sleeping at 3,500 m?

There is no evidence that all experienced athletes should progress there. Bejder et al. (2017) tested a progressive eight-hour protocol ending at 3,500 m without detecting improvements in measured cycling outcomes.

Should I aim for 88% SpO₂?

No. An 88% wearable reading is not a validated target. Context, accuracy and appropriate medical advice matter.

Can Oxygen Coach select my ideal altitude?

It can help organise and interpret available exposure and wearable trends, but no app can independently determine a universally optimal setting or promise a result.

The bottom line

The research on simulated-altitude sleeping spans roughly 2,000–3,500 m and shows mixed outcomes. Rather than treating higher as better, look at altitude × exposure hours × total nights × individual response. A well-documented programme is more meaningful than chasing the highest setpoint or lowest saturation reading.

Interested in how simulated-altitude equipment fits your training environment? Explore the Oxygen Coach altitude-training app and complete altitude bedroom guide, or contact Box Altitude for an equipment demonstration.

Research and equipment information only; not an individual altitude or medical prescription. Study settings, sample sizes, training loads and outcome measures differed. No result is guaranteed for any athlete or Box Altitude product.