Does the composition of your evening meal affect sleep quality? Original paper

In this randomized controlled trial in physically active men, the amount and type of carbohydrates in the evening meal did not influence sleep metrics.

Whether the amount or type of carbohydrates in an evening meal affects sleep quality.

The primary outcome was sleep duration. The secondary outcomes were sleep efficiency, sleep onset latency (the time it takes to fall asleep), wakefulness after sleep onset time (the total time spent during awakenings after having fallen asleep), and subjective sleep quality, daytime sleepiness, and fatigue.

Sleep metrics were assessed using polysomnography and actigraphy, while subjective sleep quality, daytime sleepiness, and fatigue were assessed using questionnaires.

42 physically active men (ages 18–48) with an average VO₂max (maximum oxygen consumption during exercise) of 45 to 51.

In this 4-week randomized controlled trial, the participants were assigned to 1 of 3 groups, which differed by amount and type of carbohydrates included in the evening meal:

• SL: No carbohydrates
• LGI: 40% of total daily carbohydrate intake from low-glycemic-index foods
• HGI: 40% of total daily carbohydrate intake from high-glycemic-index foods

The protein, fat, and vegetable contents of the meals were similar between the groups.

The meals were consumed approximately 3 hours before the participant’s usual bedtime. Five days per week, the participants ate their meal after performing evening exercise, which was completed about 4 hours before the participant’s usual bedtime. All of the participants followed the same exercise routine, which was supervised by an exercise scientist.

The participants consumed similar eucaloric diets. The diets provided 1.5 grams of protein per kg of body weight per day and 5 grams of carbohydrate per kg of body weight per day. The remaining calories were derived from fat.

There were improvements in almost all of the outcomes, in all of the groups, with no significant differences between the groups:

• Sleep onset latency decreased by approximately 46%.
• Sleep duration increased by approximately 7% (+25 minutes).
• Sleep efficiency increased by approximately 6%.
• There were fewer disruptions while sleeping (less time spent awake after falling asleep).
• Subjective sleep quality and daytime sleepiness improved.

The results suggested that doing a combination of engaging in resistance exercise and high-intensity interval training + consuming a relatively high-carbohydrate, high-protein diet can improve sleep metrics. However, the amount and type of carbohydrates in the evening meal does not seem to further those effects.