Climbing extremely high mountains requires a long time (weeks together) to acclimatisation to the altitude. Is it possible to reduce this time by adding sleeping in Altitude tent to the preparation trainings? Is altitude tent something worth buying?
Disclaimer - The answer is purely based on research. I've personally only been up to 6400m and have never used an altitude tent to acclimatise.
Background of altitude acclimatisation:
With increase in altitude, the barometric pressure decreases. This means, there's less amount of air. However, the percentage of Oxygen in itself remains the same (21%). This implies that there's lesser air to breathe, and in turn, lesser Oxygen to intake.
To mitigate this, the body produces more red blood cells to absorb more Oxygen (also the reason why blood gets thicker at altitude). This is one of the ways body mitigates the thinner air in the atmosphere at altitude.
The science of altitude acclimatisation itself is ill developed. There are hundreds of studies but nothing is set in stone.
Altitude tents (Hypoxic tents)
Hypoxic training is very common among athletes. However, there's a very important difference between hypoxic training as compared to altitude acclimatisation.
When it comes to hypoxic tents, the air thickness remains the same but the percentage of oxygen is reduced. This is a way to simulate the lesser Oxygen that's found at higher altitude. However, this is not the same as high altitude. At altitude, the air itself is thinner.
Theoretically, a hypoxic tent should be simulate the same effect as a high altitude stay. However, there are quite a few studies that suggest otherwise.
When transported to 4300 m (HH), subjects who were preacclimatized in NH had a minimal benefit (e.g., no or <1 mm Hg decrease in PETCO2 or AMS prevalence of 50%–64% instead of 80%–100% in nonacclimatized subjects). In addition, the NH preacclimatization did not induce any reduction in the acute performance decrement observed during the first 24 h after arrival at 4300 m. These results highlight a specificity of the HH condition and an (unresolved) indirect influence of the barometric pressure. Moreover, the findings show that the ventilatory acclimatization can be effective in NH, but not in HH, and that the light ventilatory and AMS benefits retained in HH for the NH preacclimatized groups did not translate to performance benefits.
Here, HH stands for Hypobaric Hypoxia (Altitude based reduction in oxygen) and NH (Normobaric Hypoxic, tent based reduction in oxygen).
There's also a study of if at all the acclimatisation that was gained using altitude would be retained by using tent based acclimatisation (The reverse of what you are asking). And here's an excerpt from the study:
These results demonstrate that HA acclimatization-induced improvements in ventilatory and hematologic responses, AMS, and cognitive function are partially retained during RA after 12 days at SL whether or not NH treatment is utilized.
RA stands for reduced altitude, SL stands for sea level, HA for high altitude
These sources are interesting as these mention that the hypoxic tents might actually not cause any improvement in acclimatisation or retaining of acclimatisation that's gained using actual altitude.
To conclude, it's really hard to say that Hypoxic tents will help you to acclimatise any better than being at a higher altitude. The science and the studies are divided themselves. There's no concrete yes or no as of now on this.
Here are a few links for further reading:
It take a few weeks to fully acclimatize.
Say the tent simulates 5000 ft. In 3-6 weeks you should be acclimatized to 5000 feet. You have a stronger starting point.
If you go to 10,000 it would still take your body about 3-6 weeks. Starting from 5000 it would be a little less than starting at 0 but not 1/2.
It lets have a higher base camp. Say you want to climb 20,000 you could have a base at 15,000 versus 10,000.
A lot of people climb without altitude training. Mt Rainier is 14,000 feet and a majority of people in WA live at sea level.
Fully acclimatize is for major peaks - like 20,000+.
I see your title is 8000 m so yes it should help.