Sleep, Appetite And Training Load

Sleep is usually filed under recovery rather than nutrition. It belongs in both, because insufficient sleep changes appetite regulation and interferes with the processes that use the food eaten.

The hormonal shift

Two hormones dominate short-term appetite regulation: one signalling hunger, secreted largely by the stomach, and one signalling sufficiency, secreted by fat tissue.

Sleep restriction raises the first and lowers the second, producing increased hunger and reduced satiety from the same quantity of food.

The shift also tends towards a preference for energy-dense, quickly absorbed foods, which is a consistent finding across sleep restriction research.

What recovery requires from sleep

Growth hormone is released in pulses concentrated in deep sleep, and it participates in tissue repair and in the regulation of protein turnover.

Muscle protein synthesis continues overnight using amino acids from the previous day, and the process is impaired when sleep is curtailed.

Glycogen resynthesis also proceeds overnight, which is part of why a poor night can leave a well-fuelled athlete feeling flat the following day.

Why athletes are particularly exposed

Training raises both recovery demand and, frequently, the difficulty of sleeping, since hard evening sessions elevate core temperature and arousal for hours afterwards.

Early sessions compress sleep from the other end, and athletes combining training with work or study routinely lose sleep from both directions.

The accumulated effect appears as poor adaptation and elevated perceived effort, which is easily misread as a training problem requiring more training.

What nutrition contributes back

Eating too little during the day frequently disturbs sleep, because hunger and low blood glucose are themselves arousing.

Caffeine has a long half-life and its effects on sleep architecture persist well past the point at which the alerting effect has faded.

Large, heavy meals immediately before bed can disturb sleep through digestive discomfort, while a moderate evening meal with protein generally does not.

Reading it correctly

Persistent unusual hunger, poor recovery and heavy sessions occurring together are worth examining as a sleep pattern before they are examined as a diet or training problem.

Sleep also interacts with the conditions that raise nutritional risk in athletes, including insufficient energy availability, and the two frequently occur together.

Persistent sleep disturbance is a matter for a clinician rather than a nutritional adjustment, particularly when it does not resolve with an ordinary reduction in load.