April 2026

I am surprised when I followed various influencers how few did a thorough altitude acclimatisation. For me, I felt it might be one of the most important things I did.

I started in November giving myself 5 months of altitude training. That meant sleeping in a tent in our spare room for 5 months (except when we were travelling or on holiday).

Before you ask, yes, I have a very patient and supportive wife.

Let’s talk through my protocol.

Hypoxic Machine

I started off buying the Metrafit hypoxic machine from the Altitude Centre. It was fine for Ama Dablam, although I did get headaches and weakness on the climb. However, it was not good enough for Everest summit.

Although it states it will get to 9% oxygen levels, or 6600m, the reality is that the pump is not powerful enough to do this if you sleep in a tent. Tents on the bed are essential.

The Hypoxico Everest Summit II is a good machine. Although I have had problems with two of them now. I bought the original second hand from eBay and it made a terrible sound and I don’t think it worked very well.

I re-sold it and bought a brand new Hypoxico Summit Everest II from The Altitude Centre. The first time I used it I did smell a slight burning, and within about 1 month there was white residue in the tube.

After about 5 weeks, there was a loud sound like the fan was hitting something. The Altitude Centre were great and provided a rental machine to keep me going until I left for Everest.

Head Tent or Full Size Tent

The smaller head tents are very cool but really they don’t work as well as the larger tents. The reason being is that when you turn on to your side, often the seal with the bed is broken and air comes in.

In a fully zippable tent that covers the whole bed, this does not happen. The head tents are also claustrophobic.

There is one advantage though. If you have a weaker hypoxic machine, then the head tent will allow lower oxygen levels as there is less space to fill.

However, sleep is important and very hard at 6600m, so I would opt for the larger bed tent that covers a standard double. The large tents are harder to put up than the smaller head tents, but the pros outweigh it.

High Altitude Adaptor

You need this for anything really high. If you are going to summit Everest you will definitely need the high altitude adaptor. It’s easy to fit and worth having in advance.

Getting to 6600m in the Altitude Tent

The guidelines state that you should be sleeping at around 2000–3000m for optimal acclimatisation. Above this, sleep is disrupted and can affect energy levels during the day.

I agree with this, however I think the benefits of sleeping at higher altitude outweigh the downsides.

What should you do?

I may be completely wrong here, but I think the higher you sleep the better—provided it is done gradually.

My progression:

Day 0–5: 2000m
Day 6–10: 2200m
Day 11–15: 2400m
Day 16–20: 2600m
Day 21–25: 2800m
Day 26–30: 3000m (End of month 1)

Day 31–35: 3200m
Day 36–40: 3400m
Day 41–45: 3600m
Day 46–50: 3800m
Day 51–55: 4000m
Day 56–60: 4200m (End of month 2)

Day 61–65: 4400m
Day 66–70: 4600m
Day 71–75: 4800m
Day 76–80: 5000m
Day 81–85: 5200m
Day 86–90: 5400m (End of month 3)

Day 91–95: 5600m
Day 96–100: 5800m
Day 101–105: 6000m
Day 106–110: 6200m
Day 111–115: 6400m
Day 116–120: 6600m (End of month 4)

Day 121–125: 6600m
Day 126–130: 6600m

I had a couple of breaks due to holidays, so total time in the tent was around 5 months.

What is it like Sleeping in an Altitude Tent?

I spent 4–5 months sleeping in an altitude tent and it is not pleasant. It is claustrophobic, hot, airless, and you need to pee frequently.

At 6600m I was waking up 4–5 times per night. I tried using a bottle in the tent, but felt light-headed and needed fresh air, so I got out each time.

You also sleep lightly. Deep sleep is unlikely, so expect reduced energy levels.

The hypoxic machines are loud, but the noise is like white noise and did not disturb me personally. If needed, you can place the machine outside your bedroom and use the long tube provided.

I also put a sock over the display to block the light.

Two Machines?

During the day, I was advised to spend 1 hour using a breathing mask at 6600m. I started with 5 minutes on/off and gradually built up.

It is hot and claustrophobic using the mask, and breathing can feel laboured, especially with less powerful machines.

You will ideally need two machines—one upstairs for sleeping and one downstairs for daytime use.

Moving a 30kg machine up and down stairs daily is impractical and risky. If you can afford it, having two machines is strongly recommended.