Is 8 Hours a Night Enough?

What the Research Says

Can sleeping at simulated altitude for eight hours a night make a difference to your training? Research involving competitive runners suggests that extended overnight altitude exposure can produce measurable physiological adaptations. But the duration of exposure, altitude level and training conditions all matter.

One of the most practical questions athletes ask about simulated altitude training is simple: How many hours do I actually need?

Traditional altitude camps often involve spending most of the day at altitude for several weeks. But for athletes balancing work, family and training, that isn’t always realistic.

An alternative is the live high, train low approach: spend evenings and nights in a simulated-altitude environment while continuing to train at or near sea level.

So what happens if you accumulate eight hours a night over six weeks?

Eight hours a night adds up to 336 hours

The total time spent at altitude is often referred to as the altitude dose.

Consider a six-week block:

Daily exposure	Six-week total
8 hours a night	336 hours
9 hours a night	378 hours
10 hours a night	420 hours
12 hours a night	504 hours

These totals are simply accumulated exposure time. They do not establish that different schedules produce equivalent adaptations.

However, the 336-hour figure is worth examining because research has investigated simulated-altitude protocols accumulating approximately 300–400 hours.

Study 1: Saunders 2009, about 400 hours of simulated altitude

One of the most relevant studies was published by Saunders and colleagues in the Journal of Science and Medicine in Sport in 2009. [1]

The Australian Institute of Sport researchers investigated whether an extended period of overnight simulated-altitude exposure could produce measurable changes in elite middle-distance runners.

The protocol

• Nine runners randomly assigned to the simulated-altitude group.
• Nine matched runners in a control group, living and training near sea level (about 600 m).
• 46 nights of exposure on average, with the number varying between runners.
• Simulated altitude of about 2,860 m.
• About 400 accumulated hours, which works out at a little under nine hours a night on average.
• Training continued near sea level.

That nightly dose is close to the eight hours in our question. The main difference is the length of the block: about 46 nights rather than 42.

What the researchers found

Compared with the control group, the simulated-altitude group showed:

• 3.2% lower oxygen consumption at the same submaximal running speeds (90% confidence interval 1.0–5.2%), a finding consistent with improved running economy.
• 3.1% lower heart rate at those same speeds (90% confidence interval 1.8–4.4%).
• A 4.9% greater increase in haemoglobin mass (90% confidence interval 2.3–7.6%), measured in nine runners against nine controls, with no placebo group.
• A 1.5% greater change in VO₂max, which the authors described as trivial and which was not statistically significant.

These figures describe the results of this specific study, not expected outcomes for individuals using home altitude equipment.

The important finding was that a prolonged nights-only exposure protocol was associated with measurable physiological adaptation, even though there was no significant improvement in VO₂max. The authors noted that the haemoglobin response was “not observed with shorter exposures”. [1]

The study was small and did not use a sham-altitude control, so its findings should not be treated as a guaranteed response.

Study 2: Neya 2013, 10 hours a night for three weeks

A second study, published in the International Journal of Sports Physiology and Performance, examined a shorter period of nightly simulated-altitude exposure. [2]

Researchers studied 14 male collegiate runners who spent 22 days training at natural altitudes between 1,300 and 1,800 m.

Seven runners also spent 10 hours per night for 21 nights at a simulated altitude of 3,000 m. The other seven stayed at 1,300 m.

What the researchers found

Compared with the control group, the simulated-altitude group showed:

• An 8.6% greater increase in absolute VO₂max (90% confidence interval 4.8–12.6%), with seven runners in each group.
• A 3.5% greater increase in haemoglobin mass (90% confidence interval 0.9–6.2%), with both groups already living and training at natural altitude.

These were between-group differences under the combined natural-and-simulated-altitude protocol, not predictions for athletes sleeping at simulated altitude while otherwise living at sea level.

The important qualification is that both groups were already training at natural altitude. The study therefore cannot establish that 10 hours a night of simulated altitude alone would produce the same results.

Nevertheless, it provides evidence that additional nightly simulated-altitude exposure can contribute to adaptations within a broader altitude-training programme.

What does the broader research say about accumulated altitude hours?

In 2013, Gore and colleagues pooled data from 17 altitude-training studies to examine how haemoglobin mass changes with accumulated exposure. [3]

Their analysis estimated an average increase in haemoglobin mass of approximately 1.1% per 100 hours of exposure. That is an average across natural and simulated altitude camps, most of which involved 14 hours a day or more at altitude, and none of which used a placebo group.

For an athlete exposed to 300 hours, the model’s 95% prediction interval for the individual response was about 1.1% to 6%.

This offers a useful way to understand why accumulated hours matter in altitude-training research, but it is not a formula that can accurately predict an individual’s response to sleeping eight hours per night.

The studies included different exposure protocols, altitudes and athletes, and not every controlled trial demonstrated a benefit.

Does that mean eight hours a night for six weeks is enough?

Six weeks at eight hours per night provides 336 hours of simulated-altitude exposure. That is a substantial cumulative duration, but the exact protocol has not been established as reliably effective.

The Saunders study offers encouraging evidence from a nights-only protocol of a similar nightly length, continued for longer. Neya 2013 provides positive findings from an additional nightly exposure combined with natural-altitude training.

There are also studies reporting no significant increase in VO₂max or haemoglobin mass after nightly simulated-altitude exposure. For example, Neya and colleagues in 2007 studied runners who trained at sea level and spent 11 hours a night for 29 nights at a simulated 3,000 m. They found no significant increase in either measure, although running economy improved by about 5%. [4]

Bejder and colleagues tested eight hours a day in altitude tents for six weeks, at simulated altitudes of 2,500 to 3,500 m, against a placebo condition, with neither the athletes nor the researchers knowing which was which. In seven highly trained triathletes, cycling power and time-trial performance did not change. [5]

Taken together, the research suggests that consistent overnight exposure can be a practical component of an endurance athlete’s altitude-training programme. It does not establish a universal minimum number of hours or guarantee a particular result.

How can you incorporate simulated altitude into your routine?

Traditional altitude camps involve travel, accommodation and time away from normal training environments.

Home simulated-altitude systems offer a different way to organise exposure.

For how to plan your nights, read How Many Hours in an Altitude Tent?

The Box Altitude Sleep Cloud fits over an existing bed, while an Altitude Bedroom System creates a simulated-altitude environment within a bedroom.

Both are designed to let athletes incorporate altitude exposure into their normal training schedules without relocating to a mountain training camp.

The Oxygen Coach app can also be used to record simulated-altitude sessions and accumulated exposure hours.

Recording hours helps athletes document their training routine. It does not, on its own, establish that physiological adaptation has occurred.

The takeaway

Eight hours a night for six weeks adds up to 336 hours.

Research by Saunders and colleagues shows that approximately 400 hours of overnight simulated altitude, a little under nine hours a night, was associated with measurable physiological adaptations in a small group of elite runners. [1]

Neya and colleagues also reported positive changes from additional nightly simulated-altitude exposure during a natural-altitude training camp. [2]

These findings support further interest in consistent overnight altitude exposure, but responses vary and the results should not be interpreted as guaranteed outcomes from any particular home system.

The practical lesson is that altitude training is about the overall programme, including exposure duration, altitude level, training and individual response, rather than simply choosing the highest altitude setting.

Explore altitude training at home

Learn how the Box Altitude Sleep Cloud and Altitude Bedroom System can fit into an existing endurance-training routine.

Explore the Sleep Cloud

Research note: The studies discussed above were performed in competitive athletes using specific simulated- or natural-altitude protocols. They did not evaluate Box Altitude equipment, and results varied. Simulated-altitude equipment is intended for training use by healthy individuals. People with relevant medical conditions should seek professional guidance before exposure.

References

1. Saunders PU, Telford RD, Pyne DB, Hahn AG, Gore CJ. Improved running economy and increased hemoglobin mass in elite runners after extended moderate altitude exposure. Journal of Science and Medicine in Sport. 2009;12(1):67–72. doi:10.1016/j.jsams.2007.08.014. PMID:18069063.
2. Neya M, Enoki T, Ohiwa N, Kawahara T, Gore CJ. Increased hemoglobin mass and VO2max with 10 h nightly simulated altitude at 3000 m. International Journal of Sports Physiology and Performance. 2013;8(4):366–372. doi:10.1123/ijspp.8.4.366. PMID:23118056.
3. Gore CJ, Sharpe K, Garvican-Lewis LA, et al. Altitude training and haemoglobin mass from the optimised carbon monoxide rebreathing method determined by a meta-analysis. British Journal of Sports Medicine. 2013;47(Suppl 1):i31–i39. doi:10.1136/bjsports-2013-092840. PMID:24282204.
4. Neya M, Enoki T, Kumai Y, Sugoh T, Kawahara T. The effects of nightly normobaric hypoxia and high intensity training under intermittent normobaric hypoxia on running economy and hemoglobin mass. Journal of Applied Physiology. 2007;103(3):828–834. doi:10.1152/japplphysiol.00265.2007. PMID:17556496.
5. Bejder J, Andersen AB, Buchardt R, Larsson TH, Olsen NV, Nordsborg NB. Endurance, aerobic high-intensity, and repeated sprint cycling performance is unaffected by normobaric “Live High-Train Low”: a double-blind placebo-controlled cross-over study. European Journal of Applied Physiology. 2017;117(5):979–988. doi:10.1007/s00421-017-3586-0. PMID:28332025.