Sleep and Fuel: What the Night Is Built On
Trail Notes | Sleep & Recovery
the night is part of the training
Sleep and Fuel
What the Night Is Built On.
Sleep and food usually sit under separate headings of recovery. The research on athletes suggests they are linked more closely than we tend to treat them.
Many of us have wondered why a solid week of training can still come with restless nights, or why the night before a race so often goes badly. This Trail Note starts from a 2014 review of sleep in elite athletes by Shona Halson, then goes back to the original studies it cites to see what they actually measured.
Most of those studies are small, many used young men, and very few involved trail runners. We use them for context, not for firm rules.
Time in bed is not the same as sleep.
In one study of Olympic athletes, sleep efficiency was lower than in non-athletes, even though their sleep measures stayed within the healthy range.
Trail Note · 01
What the research says about athletes and sleep
Sleep research on elite athletes is thin, which the review points out itself. The best-known data comes from 47 Olympic athletes across a range of sports, who wore wrist monitors and were compared with 20 non-athletes of the same age and sex.
The athletes had poorer markers of sleep quality on every measure except total time asleep, which did not differ significantly. The authors noted their sleep still sat within the range for healthy sleep.
Sleep efficiency
Athletes: 80.6%.
Comparison group: 88.7%.
Efficiency is the share of time in bed actually spent asleep.
Fragmentation index
Athletes: 36.0.
Comparison group: 29.8.
A higher number means more broken sleep.
Time asleep
Athletes: 6 hours 55 minutes.
Comparison group: 7 hours 11 minutes.
This gap was not statistically significant.
In a separate Australian Institute of Sport study, athletes and coaches ranked sleep as the most prominent cause of tiredness. The review describes 2 pinch points: the nights before important competitions, and the nights during ordinary training. Early sessions, caffeine, screens in bed and a mind that will not stop planning are all named as contributors.
These were Olympic sport athletes, not trail runners, and the groups were small. What the data supports is that sleep complaints are common in athletes. It does not tell us why they happen for us.
Lying in bed for 8 hours is an opportunity for sleep. It is not a guarantee of it.
Trail Note · 02
What a short night may cost
Most athletes do not go a full night without sleep. They lose an hour or 2, across several nights in a row. The review notes that this partial sleep loss is the more realistic scenario, and that the research on it is limited.
The full-night studies give a feel for the size of the effect. In 1 study, 11 men ran 30 minutes at a set effort, then did a 30 minute self-paced distance test. After 30 hours awake they covered 6,037m, compared with 6,224m after a normal night.
Heart rate and ratings of effort did not differ significantly between the two trials, and pacing was little changed. The drop was small, and it was measured in a lab, not on a trail.
A second study followed 10 male team sport athletes through 30 hours awake. Sprint times were slower on the second day, and muscle glycogen before exercise was lower (209 versus 274 mmol per kg of dry weight). The study cannot show that missing sleep caused the lower glycogen, but it is a reminder that sleep and fuel stores may be linked.
What happens over several short nights is closer to real life. In a study of 66 volunteers, those limited to 5 or 7 hours in bed for 7 nights lost speed on a reaction test, then levelled off at a lower baseline. After 3 nights of 8 hours in bed, they had not returned to where they started.
Heavy lifting
In 8 men limited to 3 hours of sleep for 3 nights, maximal bench press, leg press and deadlift all fell, while maximal biceps curl did not.
Submaximal lifts dropped significantly after the second night.
Appetite
In 12 young men, 2 days of restricted sleep were followed by lower leptin (18%), higher ghrelin (28%) and higher hunger (24%) and appetite (23%).
The biggest rise was for calorie-dense, carbohydrate-rich foods (33% to 45%).
Immune markers
In 36 healthy adults, sleeping under 7 hours the night before was linked with about 30% lower natural killer cell activity.
That is an association, not proof that one short night makes you ill.
Pain
A review of lab studies found that, in the majority, sleep deprivation made people more sensitive to pain.
The human data are inconsistent, so its authors would not draw firm conclusions.
Short sleep may not stop you running. It may make running feel like more work, and make the snack cupboard louder.
Trail Note · 03
The night before a race
In a survey of 632 German athletes, 66% said they had slept worse than usual at least once before an important competition. Of those, 70% had trouble falling asleep, 43% woke early and 32% woke during the night.
The reasons they gave were thoughts about the event (77%), nervousness (60%), unusual surroundings (29%) and noise (17%). Athletes in individual sports reported more problems than those in team sports, which is worth knowing if you race solo.
The reassuring part is that most of the athletes in that survey said disturbed sleep did not affect their performance. The review also cites older work where a single restricted night affected reaction-based tasks, while strength and endurance running held up. It is early evidence, so we treat it as a reason not to panic, not a reason to stop caring about sleep.
Our coaching view is to protect the 2 to 3 nights before race eve rather than chase a perfect last night. Race Week Tips for Trail Runners and Journal Prompts: The Final 10 Days Before Your Race cover the rest of race week.
Trail Note · 04
Extra sleep, naps and the nights after a big effort
The research also looks at the flip side: what happens when athletes get more sleep. In a study of 11 men on a university basketball team, players aimed for 10 hours in bed for 5 to 7 weeks and slept about 111 minutes more a night. Their sprint time improved from 16.2 to 15.5 seconds, free throw accuracy rose 9%, and mood and sleepiness scores improved.
This was a small study of 1 team in a skill and sprint sport, with no comparison group, so it says little about long trail efforts directly. It does point in a consistent direction.
Naps
In 10 men limited to 4 hours of sleep, a 30 minute lunchtime nap improved alertness, memory and 20m sprint time (3.97 to 3.88 seconds). Grip strength and reaction time did not change.
In another small study, a nap or a 10 hour recovery night brought raised white blood cell counts back near baseline after a 2 hour night, while a standard 8 hour night did not.
More sleep over time
Small studies suggest more sleep across several weeks can lift performance and mood.
In a heavy block, an earlier bedtime may be worth more than 1 extra session.
After a big day
In a 1981 study of athletes after a 92km road race, total sleep time and slow-wave sleep both rose over the next 4 nights.
Your body may spend extra sleep on repair after a long effort.
Her Trails coaching cue
If the night after a big long run is broken, plan an earlier bedtime for the 2 nights that follow. Your body may be asking for more sleep, not less.
Trail Note · 05
Food and sleep: what is and is not known
The nutrition research on sleep is small, mixed and mostly done in healthy volunteers over days, not months. The review says so plainly. What follows is where the findings lean, not a prescription.
Carbohydrate
In 12 men, a high glycemic index rice meal 4 hours before bed cut the time to fall asleep to 9.0 minutes, compared with 17.5 minutes after a low glycemic index meal. Eating it 1 hour before bed gave 14.6 minutes.
In a crossover study of 36 young adults, a high carbohydrate diet was linked with shorter time awake at night. A 48 hour very low carbohydrate diet in 14 men reduced the share of REM sleep.
Fat
In 459 postmenopausal women, higher fat intake was among the dietary factors linked with shorter actigraphy sleep time.
In the 36 adult crossover study, a high fat diet was linked with better reported sleep quality. The studies disagree, so we would not act on either.
Energy and variety
In a national survey, people sleeping under 5 hours ate 2,036 kcal a day on average, compared with 2,151 kcal for normal sleepers, and ate a narrower range of foods (14.0 versus 17.8).
This is a survey snapshot, not a cause. Our note Not Under-trained. Under-fuelled. covers why enough fuel matters for women training hard.
The practical summary is modest. The best-controlled trial gave jasmine rice to 12 men, so the wider list of higher glycemic foods, such as white rice, bread and potatoes, is an inference. The timing finding leans towards a few hours before bed rather than just before.
If you are in a taper, How to Fuel Taper Properly as a Female Athlete covers the food side of race week.
Trail Note · 06
Tryptophan, melatonin and herbs
Tryptophan is the amino acid the body uses to make serotonin, and then melatonin. In the studies the review covers, doses as low as 1g improved time to fall asleep and subjective sleep quality. The review gives about 300g of turkey or about 200g of pumpkin seeds as food sources of that amount.
Melatonin
A meta-analysis found melatonin shortened time to fall asleep by about 12 minutes overall, and by about 7 minutes in people with insomnia. Its authors concluded it was not effective for most primary sleep disorders in the short term.
The authors found no evidence of adverse effects in short-term use (3 months or less).
Tart cherry juice
In 20 healthy adults, 7 days of tart cherry concentrate raised urinary melatonin and improved sleep time and efficiency. In 15 older adults with insomnia, only time awake after falling asleep improved against placebo.
Both studies were small, and the effects were modest.
Valerian
A meta-analysis of 16 trials and 1,093 people found reports of better sleep quality (relative risk 1.8).
The authors noted significant methodological problems and signs of publication bias, so treat it as unproven.
Before you buy anything
The review flags that supplements can carry contaminants, and that some ingredients carry an inadvertent risk of a positive drug test if you race in tested events.
Talk with a GP or pharmacist first, especially if you take other medication. Food first. Supplements are the last layer, not the first.
Trail Note · 07
A coaching lens
Sleep rarely changes because of 1 thing. It shifts when a few small habits stack up over weeks. Here is where we would start.
Eat enough, all day
Low energy intake may disturb sleep, so start with enough food across the day before adjusting anything at night.
After a short night, expect hunger to be louder. Plan your snacks before the tiredness does.
Time the evening meal
Where your day allows, eat dinner with carbohydrate a few hours before bed, rather than a large meal close to it.
Plan the race eve
Pack what removes the known disruptors: your own pillow, earplugs and an eye mask. Expect a restless night, and bank sleep in the 2 to 3 nights before.
Use naps on purpose
A 30 minute nap earlier in the day may help after a short night. If it makes falling asleep harder that evening, shorten it or skip it.
For how sleep can shift across the menstrual cycle and the menopausal transition, read Sleep, Hormones and Athletic Performance in Women. If your sleep stays disrupted for weeks despite the basics, that is worth a conversation with your GP.
Her Trails coaching cue
Look after the day to protect the night. Enough food, an earlier bedtime and a plan for the nights that matter will do more than any single tweak.
Fuel the day. Protect the night. Let the training land.
fuel the day, protect the night
Keep going with us
Run with us on Sundays and meet the women training beside you.
See what is coming next from Her Trails Coaching.
