Climbing Lhotse on circadian time

Megan Rath is a former Ironman and Olympic-distance triathlete turned mountaineer. After five knee surgeries, she rebuilt her career as an endurance athlete and went on to complete the Seven Summits — including Everest — one of fewer than 100 women to do so.

Now she is returning to Everest to climb Lhotse, the fourth-highest mountain in the world, on a compressed timeline with little room for error. At 27,939 ft, it is a technical, high-risk ascent that shares Everest's route through the Khumbu Icefall, with constant exposure to avalanches and falling rock.

To make it possible, she is going beyond standard preparation — aligning her body's circadian clocks to the climb and treating circadian rhythms as a performance system. The goal: Peak at the summit.

The science behind the climb

Climbing Lhotse is a full-body physical and mental challenge. But one critical variable is often overlooked: The circadian clocks.

Circadian rhythms regulate nearly every biological system in our brain and body. The central circadian clock in our brains determines alertness, sleepiness, and when we perform at our best. Megan's journey — long-haul travel, extreme altitude, and irregular light exposure on overnight treks — will disrupt her circadian rhythms at every stage.

Circadian time, which is different from clock time, is synchronized by light. Timed correctly, light exposure or darkness can shift the body clock earlier or later to align with one's goals — in this case, Megan's Lhotse climb schedule. Timed incorrectly, it can push the body clock in the wrong direction, making your rhythms work against you and impairing performance.

With Timeshifter on her side, Megan is following a precise plan for when to seek light and when to avoid it — through sunlight or man-made light, sunglasses, and sleep — so her body is performing at its best for every climb and, ultimately, the summit push.

The route is set

Timeshifter maps the biology.

New York
→ Istanbul
→ Kathmandu
→ Khumjung (furtnebach acclimitzation)
→  Island Peak (furtnebach acclimitzation))
→ Everest Base Camp
→ Lhotse Face
→ Summit

Key dates*

Apr 29  — Departure: EWR → Istanbul → Kathmandu
May 1-13 –– Acclimatization: overnight stays across increasing altitudes via helicopter transfers
May 13 — Arrive Everest Base Camp  
May 14 –– Begin Trek
May 18  –– Summit Lhotse!
May 19-24 –– Descent
May 24 — Return: Kathmandu → Istanbul  → Home

* All dates subject to change. Built for real-world conditions, Megan’s Timeshifter plan will be continously adjusted to address delays, weather, and the unpredictability of the mountain.