Effect of sleep duration on dietary intake, desire to eat, measures of food intake and metabolic hormones: A systematic review of clinical trials.

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• Reduced sleep duration may serve as a mediator for weight gain in part due to increased appetite, increased fat intake and disruptions to energy balance.
• Enhancing sleep quality may serve to support weight loss protocols.

Introduction

Short sleep duration and disruptions to circadian rhythm have been associated with being overweight and obese. It has been suggested that sleep restriction may interfere with appetite regulating hormones leading to increased appetite and disrupted energy balance.

This study aimed to systematically review studies exploring the relationship between sleep duration and food consumption, energy intake, anthropometric characteristics and appetite-regulating hormones.

Methods

This systematic review included 50 randomised controlled trials including 3,387 participants.

Results

Energy intake

• 13 out of 30 the included studies found that short sleep conditions led to higher energy intake.
• 1 study identified that sleep restriction resulted in a 15.3% and 9.2% increase in energy intake in both women and men.
• 3 studies noted that prolonging sleep duration led to a reduction in energy intake.
• 1 study reported a reduction in energy intake after sleep restriction (P=0.031).

Fat consumption

• 9 studies out of 22 identified a significant association between short sleep and increased fat consumption.
• 7 studies did not identify a difference between groups.
• 3 studies noted a decrease in fat consumption following prolonged sleep (P<0.001, P<0.05, P=0.04).

Hunger and appetite

• 11 studies out of 17 observed that sleep restriction resulted in increased hunger ratings.
• 3 studies found an increase in appetite following sleep restriction (P<0.01) with 3 finding no difference..
• 1 study reported a decrease in appetite following sleep restriction.
• 2 studies noted that portion sizes increased as a result of sleep restriction (P<0.01).
• 1 study reported an increase in eating occasions following restricted sleep compared to habitual sleep (6.08 vs 4.96).

Body weight

• 6 studies out of 14 found no effect of sleep loss on body weight.
• 4 studies identified that sleep restriction led to weight gain (P<0.001, P<0.05, P=0.14, P=0.031).
• 2 studies reported weight loss following increased sleep duration (P<0.001).

Ghrelin and leptin

• Leptin and ghrelin levels were generally not found to be influenced by sleep duration, with the exception of a few studies.

Reduced sleep duration may promote weight gain by:

• Increasing energy intake.
• Increasing fat consumption.
• Increasing hunger and appetite.
• Increasing portion sizes and eating occasions.

Prolonging sleep duration may support weight loss by:

• Reducing energy intake.
• Reducing fat intake.

• Mixed results on the influence of sleep restriction on appetite regulating hormones, leptin and ghrelin.
• Some studies noted the negative impact of sleep restriction on leptin and ghrelin concentrations, collectively shortened sleep duration did not appear to influence these hormones.
• Further sleep restriction studies exploring additional appetite regulating hormones and neuropeptides and the reward system may provide a more definitive understanding of the underlying mechanism for reduced sleep duration to disrupt the appetite and energy balance and promote weight gain.