Why You Feel So Tired in Aspen (And How to Get Your Energy Back)
If you’re unusually tired in Aspen — napping in the afternoon, sleeping badly, or feeling wiped out by things that wouldn’t touch you at home — that’s one of the most common effects of altitude, and it’s not a fitness problem. Your body is working harder at rest than it does at sea level, and it’s doing it around the clock.
Most people feel substantially better by day three or four. Here’s why it happens and what actually shortens it.
Why does altitude make you so tired?
Three things stack up at once, and each compounds the others.
Your body is doing more work at rest. At 7,908 feet, your heart beats faster and your breathing rate increases even when you’re sitting still. That baseline effort continues 24 hours a day, and it burns energy you’d normally have available for skiing, hiking, or just getting through the day.
Your sleep is worse than you think. Many people at altitude experience periodic breathing during sleep — a cycle where breathing deepens, pauses briefly, then restarts. It fragments sleep without necessarily waking you fully. You can spend eight hours in bed and get considerably less restorative sleep than that number suggests.
You’re dehydrated. The air here is dry enough that you lose meaningful water through breathing alone, before accounting for exertion. Dehydration produces fatigue on its own and makes everything else worse.
Is this altitude sickness or just tiredness?
Fatigue is one of the recognized symptoms of acute mountain sickness, which affects up to 40% of people who ascend to around 8,000 feet. But fatigue alone, without other symptoms, is more often simple altitude adjustment.
It’s more likely to be acute mountain sickness if the tiredness comes with a headache — the most common first symptom — plus any of nausea or poor appetite, lightheadedness, or unusual breathlessness.
If you’re only tired and otherwise feel fine, you’re most likely acclimatizing normally.
What actually helps you get your energy back?
Fix your sleep first. It’s the highest-leverage change. Avoid alcohol and sleeping pills for the first 48 hours — both suppress breathing, which is precisely the opposite of what your body needs overnight. Many guests find supplemental oxygen while sleeping is the single most effective intervention, because it addresses the reason sleep is poor rather than working around it.
Drink more water than feels necessary. Not sports drinks, not coffee. Plain water, consistently through the day.
Eat more carbohydrate than usual. Carbohydrate requires slightly less oxygen to metabolize than fat does, and appetite often drops at altitude just when you need fuel most. Eat even if you don’t feel like it.
Reduce your ambitions for day one and two. The single most reliable way to feel terrible on day three is to go hard on day one. Save the big ski day or the long hike.
Get outside in daylight in the morning. It helps reset a circadian rhythm disrupted by travel, and it addresses the jet-lag portion of the tiredness that has nothing to do with elevation.
How long does altitude fatigue last?
Most otherwise healthy adults notice a clear improvement by day three or four as acclimatization progresses. Energy is often the last thing to return — headache and nausea usually resolve before you feel fully like yourself again.
Some people take longer, and it doesn’t track with fitness. Endurance athletes are not reliably better at altitude than anyone else, and someone who felt fine on a previous trip can struggle on the next one. Age and any lung or heart condition do matter, and those groups often benefit from having oxygen available for the entire stay.
If you’re getting more tired rather than less as the days pass, that’s worth a conversation with a clinician rather than pushing through.
Need oxygen in Aspen or Snowmass?
Oxygen Now delivers medical-grade oxygen to homes, hotels, and rentals across Aspen and Snowmass, often the same day. We’re physician-owned — founded and led by Dr. Kirk Mahon, a board-certified emergency physician.
Call or text (970) 236-6464
See our oxygen rental equipment · Read the altitude and oxygen FAQ · Learn about altitude sickness symptoms and treatment
This article is for general information and is not a substitute for medical evaluation.
