An emerging field of research has revealed a bidirectional relationship between sleep and diet, highlighting the potential role of a healthy diet in improving sleep. However, the impact of chrono-nutrition on sleep remains less explored. Here we conducted a systematic scoping review, considering the multiple dimensions of chrono-nutrition, to describe the extent, range, and nature of the existing literature in this area (PROSPERO: CRD42021274637). There has been a significant increase in the literature exploring this topic over the past six years (almost 67 % of the evolving literature). A breakdown of the included studies was performed according to three major chrono-nutritional dimensions: meal timing [n = 35], irregular eating patterns [n = 84], and frequency of eating occasions [n = 3]. Meal timing included three sub-dimensions: breakfast skipping [n = 13], late eating [n = 16], and earlier vs later meals schedules [n = 6]. Irregular meal patterns included three sub-dimensions: diurnal fasting [n = 65], intermittent fasting [n = 16], and daily meal patterns [n = 3]. Frequency was the least studied dimension (n = 3). We provided a synthetic and illustrative framework underlining important preliminary evidence linking the temporal characteristics of eating patterns to various facets of sleep health. Nonetheless, much work remains to be done to provide chrono-nutrition guidelines to improve sleep health in the general population.

This study compares the effectiveness of a 12-week moderate exercise training program (METP), performed in the morning versus the evening, on sleep, physical activity, physical fitness, sleepiness, fatigue and health-related quality of life (HRQoL) in overweight and obese patients. Sedentary and inactive overweight/obese adults (n = 36) were included in METP and randomized into two groups: morning group (GM) and evening group (GE). Twenty-eight participants successfully completed METP (3 × 90 min exercise session per week for 12 weeks, completion rates >80%). Sleep, physical activity, and bedtime temperature were measured using accelerometry and infrared tympanic temperature during 3 separate weeks of the study (Week1, Week6, and Week12). Participants also took part in baseline and endpoint assessments including physical fitness as well as subjective physical activity, chronotype, sleep quality, sleepiness, fatigue and HRQoL. METP did not impact objective sleep quality differently between the two groups (morning vs evening). Bedtime and mid-sleep were advanced when METP was done in the morning whereas they were delayed when METP was practiced in the early evening (p = .003). Beside this finding, no valuable differences between the two groups were noted in all the remaining measures. METP resulted in improvements of body composition, cardiorespiratory and muscular endurance, as well as a favorable impact on subjective sleep quality, diurnal sleepiness, fatigue and HRQoL in both groups (all p < .05). Evening METP could be an effective alternative for overweight/obese adults when morning METP is not possible.

Disturbed sleep is common in adolescents. Ingested nutrients help regulate the internal clock and influence sleep quality. The purpose of this clinical trial is to assess the effect of protein tryptophan (Trp)/large neutral amino acids (LNAAs) ratio on sleep and circadian rhythm. Ingested Trp is involved in the regulation of the sleep/wake cycle and improvement of sleep quality. Since Trp transport through the blood–brain barrier is competing with LNAAs, protein with higher Trp/LNAAs were expected to increase sleep efficiency. This randomized double-blind controlled trial will enroll two samples of male adolescents predisposed to sleep disturbances: elite rugby players (n = 24) and youths with obesity (n = 24). They will take part randomly in three sessions each held over a week. They will undergo a washout period, when dietary intake will be calibrated (three days), followed by an intervention period (three days), when their diet will be supplemented with three proteins with different Trp/LNAAs ratios. Physical, cognitive, dietary intake, appetite, and sleepiness evaluations will be made on the last day of each session. The primary outcome is sleep efficiency measured through in-home electroencephalogram recordings. Secondary outcomes include sleep staging, circadian phase, and sleep-, food intake-, metabolism-, and inflammation-related biochemical markers. A fuller understanding of the effect of protein Trp/LNAAs ratio on sleep could help in developing nutritional strategies addressing sleep disturbances.

Study Objectives: To examine the effect of the timing of high-intensity exercise (afternoon vs. evening) on adolescent athletes’ bedtime psychological state, sleep quality, sleep staging, and next-day wellness/sleepiness according to chronotype. Methods: Forty-two young athletes (morning type: n = 12, intermediate type: n = 14; evening type: n = 16) completed a randomized crossover study under free-living conditions. The counterbalanced sessions include: (AEX) afternoon (1:00–3:00 p.m.) and (EEX) evening (5:30–7:30 p.m.) high-intensity exercise. Sessions were conducted over three days each and were separated by a 1-week washout period. The time in bed was fixed (10:30 p.m.–7:30 a.m.). Sleep was assessed through ambulatory polysomnography. Results: The effect of high-intensity exercise on sleep differs significantly depending on the time of exercise with lower sleep efficiency: SE (−1.50%, p < .01), and higher SOL (+4.60 min, p ≤=< .01), during EEX vs. AEX. Contrary to the previous view, we discovered differences in the mediated response based on the chronotype of young athletes. These differences were observable in the psychological state at bedtime, objective sleep, and the next day’s self-reported wellness. Whereas the sleep of participants with a late chronotype remains stable regardless of the time of exercise, those with an early chronotype experience higher mood disturbances and clinically significant sleep disruptions following evening high-intensity exercise. Conclusions: Exercise timing and chronotype affect the psychological state at bedtime and objective sleep in adolescent athletes. This also alters next morning signs of pre-fatigue and wellness which suggest that the consideration of both features is important to adolescent athletes’ recovery.