Are there foods you should avoid eating before going to bed?

Alcohol and caffeine are the two biggest culprits. Both are categorically identified as disruptive to sleep. Caffeine is found not only in coffee, but also in tea, soft drinks and energy drinks. Energy drinks score doubly poorly: they combine high caffeine levels with a lot of sugar. The effect of alcohol may seem harmless because it makes you drowsy, but it disrupts sleep architecture and leads to lighter, less restorative sleep.

Fatty meals close to bedtime are also linked to poorer sleep quality, although the type of fat plays a role here. Saturated fats, such as those found in fast food, red meat and full-fat dairy products, are associated with worse sleep. Unsaturated fats, such as those in nuts, olive oil and fish, do not appear to share that negative link. This relationship is observational, however: it comes from population studies, not from controlled experiments.

On a positive note, a dietary pattern rich in fibre, vegetables, fruit and anti-inflammatory nutrients, such as a Mediterranean diet, is associated with better sleep quality. This too is associative evidence, but the consistency across multiple studies is good reason to take it seriously.

In practical terms, the clearest recommendations are: avoid caffeine in the hours before bedtime, do not drink alcohol as a nightcap, and opt in the evening for lighter meals without much saturated fat. The precise figures, such as exactly what time to stop or how many grams of fat are still acceptable, are not known from the available studies.