Sleeping in ultra-trail: should you stop or run without sleeping?

From 12 hours of racing, the question of sleep already starts to come up. And the longer the effort goes on—24, 48, 72 hours or more—the more it becomes central. Fatigue doesn’t just come from your legs. It hits when your brain gets foggy, when your eyes close against your will, and every step becomes a battle. And just like with your legs, not all runners are equal when it comes to sleep. Some fall asleep before even 24 hours of effort. Others hold on until hallucinations kick in. And then there are those extreme-format runners, like the Backyard runners, capable of going up to 119 hours (five days!) with only a few micro-naps of a few minutes. ## What impact does sleep have on performance? Sleep deprivation acts like intoxication. After more than 24 hours awake, your alertness drops as much as if you’d had several drinks. The result: loss of clarity, slower reflexes, navigation errors. On a technical descent, that can mean a fall. At night, a missed marker. There are also hallucinations, well known to ultra-trailers. When your brain invents to compensate, it distorts your perception: terrain shapes change, shadows turn into figures, and every landmark becomes uncertain. And of course, sleeping means stopping, and that costs time and places. Sleeping or not isn’t just a comfort issue. It’s an element to factor into your strategy just like your nutrition or hydration. ## How to manage fatigue in long-distance races? Depending on the distance, you can choose different strategies to handle fatigue during your ultra: - Micro-naps (5 to 20 minutes): by the side of the trail, at a base camp, sometimes even with your head on your pack, a micro-nap has a real “reset” effect on the brain: even 5 minutes help recharge your energy. 💡 Tip: set an alarm (watch or phone) to fully relax without fearing you won’t wake up. - Long naps (30 to 60 minutes): best for races where you’ll spend at least 2 nights outside (Tor des Géants, Barkley, Grand Raid). 💡 Tip: favor base camps, quiet places with a mattress, blanket, and possibly earplugs to escape noise. If you sleep by the trail, move aside to avoid being disturbed. - Real sleep: on races lasting 3 days or more, allowing yourself real sleep blocks of 3 to 5 hours can be a winning strategy. Some runners manage without, but for most, it’s better to sleep a few hours than drag yourself all day in a drowsy 3 km/h mode. 💡 Tip: prioritize night sleep. In races, you usually move slower in the dark, so you lose less time sleeping then. In some specific contexts, like the desert, do the opposite: take advantage of the cool night to run, and sleep during the day when temperatures are crushing. ## How to prepare for fatigue beforehand? There’s no miracle solution for sleep. But if you’re prepping for an ultra-trail, anticipating fatigue already stacks the odds in your favor to make it to the finish. ### Build a “sleep bank” The nights before an ultra are crucial. You can’t stockpile several days of sleep in advance, but sleeping more 2 to 3 nights before the race helps reduce your deficit at the start. Conversely, staying up late or sleeping poorly the night before an ultra can cost you dearly from the first night outside. ### Train to run tired Include sessions early in the morning or late at night to get your body and mind used to night effort. In the months before the race, you can also join races with a night start or late finish: a great way to get used to the night race context. ### Plan your strategy in advance Like your nutrition, plan when and where you might sleep (base camp, refuge, or just a quiet 10-minute break). A plan adapts and changes, but better a plan than nothing. This at least lets you think about it based on your abilities: whether you’ll allow yourself micro-naps or longer sleep blocks. Then the “where” and “when” will be decided on the ground. ### Equip yourself smartly Sleep in ultra is inseparable from minimal comfort: - A reliable headlamp to avoid mistakes at night, - An appropriate jacket so you don’t shiver if you stop for a few minutes, - A lightweight mattress for more comfort at base camp, - A 2-in-1 sleeping bag for cold nights, - Safety gear to calmly manage a break in case of trouble. ## Conclusion In ultra-trail, fatigue and sleep are part of the race. It’s a factor to manage like your nutrition or gear. The real question isn’t “to sleep or not?” but to anticipate fatigue with a strategy, tested in training, and adapt to stay clear-headed until the finish line.