Isocaloric Diets with Different Protein-Carbohydrate Ratios: The Effect on Sleep, Melatonin Secretion and Subsequent Nutritional Response in Healthy Young Men

Abstract

This study aimed to determine the short-term effect of two isocaloric diets differing in the ratio of protein−carbohydrate on melatonin levels, sleep, and subsequent dietary intake and physical activity in healthy young men. Twenty-four healthy men took part in a crossover design including two sessions of three days on isocaloric diets whether high-protein, low-carbohydrate (HPLC) or low-protein, high-carbohydrate (LPHC) followed by 24-h free living assessments. Sleep was measured by ambulatory polysomnography pre-post-intervention. Melatonin levels were assessed on the third night of each session on eight-point salivary sampling. Physical activity was monitored by accelerometry. On day 4, participants reported their 24-h ad-libitum dietary intake. LPHC resulted in better sleep quality and increased secretion of melatonin compared to HPLC. A significant difference was noted in sleep efficiency (p < 0.05) between the two sessions. This was mainly explained by a difference in sleep onset latency (p < 0.01) which was decreased during LPHC (PRE: 15.8 ± 7.8 min, POST: 11.4 ± 4.5 min, p < 0.001). Differences were also noted in sleep staging including time spent on REM (p < 0.05) and N1 (p < 0.05). More importantly, REM latency (PRE: 97.2 ± 19.9 min, POST 112.0 ± 20.7 min, p < 0.001) and cortical arousals (PRE: 7.2 ± 3.9 event/h, POST 8.5 ± 3.3 event/h) increased in response to HPLC diet but not LPHC. On day 4, 24-h ad-libitum energy intake was higher following HPLC compared to LPHC (+64 kcal, p < 0.05) and explained by increased snacking behavior (p < 0.01) especially from carbohydrates (p < 0.05). Increased carbohydrates intake was associated with increased cortical arousals.

Keywords: REM sleep; cortical arousal; macronutrient; tryptophan.

Figure 1

Study overview. (A) A randomized, crossover study design including two sessions on isocaloric diets whether HPLC or LPHC. (B) Each session comprised three days of intervention during which sleep was measured by polysomnography. Salivary samples were collected on the third day of each session from melatonin assessment. The intervention was followed by 24-h free living evaluation of physical activity, and ad-libitum dietary intake; SB: sedentary behavior.

Figure 2

The time courses of salivary melatonin secretion and area under the curve (AUC) in HPLC vs. LPHC diets. HPLC: high-protein, low-carbohydrate; LPHC: low-protein, high carbohydrate. *: significant difference (HPLC vs. LPHC) with p < 0.05. **: significant difference (HPLC vs. LPHC) with p < 0.01. ***: significant difference (HPLC vs. LPHC) with p < 0.001.

Figure 3

REM latency and arousals variation in response to HPLC vs. LPHC diets. Data are shown as median ± interquartile range with scatter-plots representing individuals’ data. p value: ** p < 0.01; *** p < 0.001.