How Much to Sleep, by Format
These are our planning defaults for a first race in each format. Every minute asleep is a minute off the clock, so the budget is the least sleep that keeps you safe on the course. Martin and colleagues surveyed 636 ultramarathon runners; in 221 race reports, more in-race sleep went with slower finishes in races of 36–60 hours (r = 0.48) and over 60 hours (r = 0.44). Faster runners sleep less, but that does not make staying awake safe for you.
| Format | Planned sleep | How to take it |
|---|---|---|
| 24-hour | None | One 20-minute nap only if sleepiness makes you unsafe |
| 48-hour | 1–3 hours in total | Push through night one; one 90-minute sleep on night two, plus 20-minute naps as needed |
| Six-day | 2–4 hours a night | One or two 90-minute blocks in the small hours, every night from night one |
| Backyard ultra | None on night one | From night two, 5–10 minute naps in the gap between yards; run 50–55 minute yards to make room |
| 200-mile | 4–8 hours in total | 20-minute or 90-minute naps at aid stations, with the longer ones on nights two and three |
Sleep before you have to. Plan the long sleep for the small hours, when the body clock is lowest and walking pace drops anyway, and take it before sleepiness forces the stop. In a six-day race, sleep from the first night: staying awake for 36 hours to bank distance leaves a debt that every following night has to repay.
If you have a sleep disorder, a heart or neurological condition, or take medication that affects alertness, talk to your doctor before you plan any sleep restriction.
Nap for 20 or 90 Minutes
Brooks and Lack gave 24 healthy young adults, after a night restricted to about 5 hours, naps of 5, 10, 20 or 30 minutes; the 30-minute nap caused a spell of impaired alertness on waking. Naps of 10–20 minutes improved alertness without that grogginess. A full sleep cycle lasts about 90 minutes, so a 90-minute sleep usually ends in lighter sleep too. The in-between lengths, 30–60 minutes, are the ones most likely to end in deep sleep and a slow, confused restart.
- Short nap: set the alarm for 25 minutes from lying down, which gives about 20 minutes asleep.
- Long sleep: set it for 95–100 minutes, which allows for falling asleep and one full cycle.
- Before lying down: dry top, warm layer, shoes off, feet checked, food ready for waking.
- On waking: sit for two minutes, eat something, then stand and walk 50 m with the crew watching. Restart only if speech, balance and orientation are normal.
- After the race: someone else drives.
Do not take sleeping tablets during a race. They extend grogginess after waking and can interact with exertion and dehydration.
A Worked Sleep-Operations Sheet
This example is for a 48-hour loop race with a two-person crew.
| Field | Completed example | Fill in your plan |
|---|---|---|
| Place | Organizer-permitted crew tent beside base; confirm access before the start. | Permitted location and backup: ______ |
| Planned sleeps | Night two: 90 minutes from about 02:00. 20-minute naps at any point the runner weaves or nods off while walking. | Planned sleeps and trigger for a nap: ______ |
| Responsible person | Alex handles the stop; Sam takes over only after an explicit handoff. | Primary and backup helper: ______ |
| Before rest | Log arrival, set the alarm (25 or 100 minutes), prepare dry layers and warm food. | Alarm length and supplies: ______ |
| Wake-up check | Helper stays while the runner sits, eats, stands and walks 50 m. No restart until speech and balance are normal. | Who checks and records the decision: ______ |
| Unexpected change | A closed tent means using the backup; a warning sign means stopping and contacting race medical staff. | Backup place and medical contact: ______ |
| Crew handoff | Write actual sleep times and caffeine already taken, with product and milligrams. | Log location and next helper: ______ |
| After the race | Sam drives; arrange another driver if Sam is also too tired. | Driver and backup transport: ______ |
Download the blank sleep-operations worksheet to complete and print. Add locations and arrival windows to the crew and drop-bag planner, and rehearse finding the rest area while alert.
Kishi and colleagues ran a cross-sectional survey of 1,154 finishers of two mountain ultramarathons, one of 111 km and one of 165 km. It describes what runners did; the nap lengths above come from the laboratory nap research, not from that study.
Caffeine: How Much and When
The ISSN position stand finds 3–6 mg/kg effective and reports frequent side effects at about 9 mg/kg. For ultras it recommends holding caffeine back for the later stages and using small repeat doses. Our default, the same as in the 24-hour nutrition guide:
- First 10 hours: none.
- Overnight: about 50 mg per hour, or one 1–2 mg/kg dose (70–140 mg at 70 kg) every two hours.
- Before a planned sleep: nothing in the 2–3 hours beforehand, or the sleep will be poor.
- Multiday races: the same overnight dose each night; skip daytime caffeine so it keeps working.
Count coffee, cola, gels and tablets in the total, and use only products you have tested in training. Skip caffeine if it causes palpitations, tremor or worse nausea, and check with your doctor first if you are pregnant, have a heart condition or take interacting medication.
When Sleepiness Means Stop
Falling asleep while moving, hallucinations, confusion, repeated falls or loss of coordination mean stop in a safe place and get race medical staff. Do not treat these as ordinary tiredness without an assessment: low blood sodium, heat illness, hypothermia and low blood sugar can look the same. Crew should not wait to see whether a nap or caffeine fixes them. The full list is in the medical red flags.
Sources
- Martin, T. et al. (2018). Sleep habits and strategies of ultramarathon runners. PLOS ONE, 13(5), e0194705.
- Brooks, A. & Lack, L. (2006). A brief afternoon nap following nocturnal sleep restriction: which nap duration is most recuperative?. Sleep, 29(6), 831–840.
- Kishi, A. et al. (2024). Sleep and Ultramarathon: Exploring Patterns, Strategies, and Repercussions of 1,154 Mountain Ultramarathons Finishers. Sports Medicine - Open, 10(1), 34.
- Benchetrit, S. et al. (2024). Sleep deprivation, extreme exertion, and cognition at a backyard ultra. PLOS ONE.
- Hurdiel, R. et al. (2015). Sleep deprivation, strenuous exercise, and cognitive performance at UTMB. Journal of Sports Sciences.
- Guest, N.S. et al. (2021). ISSN position stand on caffeine and exercise performance. Journal of the International Society of Sports Nutrition.
Frequently Asked Questions
When should you stop caffeine before a planned sleep?
Two to three hours before. Caffeine taken closer to a planned 90-minute sleep makes it harder to fall asleep and lighter when you do, which wastes the stop. Resume at the overnight dose of about 50 mg an hour after you wake.
How much should you sleep in a 48-hour race?
Plan 1–3 hours in total. A common shape is one 90-minute sleep on the second night plus one or two 20-minute naps when sleepiness peaks. In a survey of 636 ultrarunners, more in-race sleep went with slower finishes in 36–60 hour races, so sleep only what keeps you safe and moving.
Can caffeine replace sleep?
No. Caffeine improves alertness for a few hours but does not repay sleep debt. If you are falling asleep while moving, stop and nap or get assessed; do not take another dose and keep going.