Chronic Insufficient Sleep Has a Limited Impact on Circadian Rhythmicity of Subjective Hunger and Awakening Fasted Metabolic Hormones

Abstract

Weight gain and obesity have reached epidemic proportions in modern society. Insufficient sleep-which is also prevalent in modern society-and eating at inappropriate circadian times have been identified as risk factors for weight gain, yet the impact of chronic insufficient sleep on the circadian timing of subjective hunger and physiologic metabolic outcomes are not well understood. We investigated how chronic insufficient sleep impacts the circadian timing of subjective hunger and fasting metabolic hormones in a 32-day in-laboratory randomized single-blind control study, with healthy younger participants (range, 20-34 years) randomized to either Control (1:2 sleep:wake ratio, 6.67 h sleep:13.33 h wake, n = 7, equivalent to 8 h of sleep per 24 h) or chronic sleep restriction (CSR, 1:3.3 sleep:wake ratio, 4.67 h sleep:15.33 h wake, n = 8, equivalent to 5.6 h of sleep per 24 h) conditions. Participants lived on a "20 h day" designed to distribute all behaviors and food intake equally across all phases of the circadian cycle over every six consecutive 20 h protocol days. During each 20 h day, participants were provided a nutritionist-designed, isocaloric diet consisting of 45-50% carbohydrate, 30-35% fat, and 15-20% protein adjusted for sex, weight, and age. Subjective non-numeric ratings of hunger were recorded before and after meals and fasting blood samples were taken within 5 min of awakening. Subjective levels of hunger and fasting concentrations of leptin, ghrelin, insulin, glucose, adiponectin, and cortisol all demonstrated circadian patterns; there were no differences, however, between CSR and Control conditions in subjective hunger ratings or any fasting hormone concentrations. These findings suggest that chronic insufficient sleep may have a limited role in altering the robust circadian profile of subjective hunger and fasted metabolic hormones.

Clinical trial registration: The study was registered as clinical trial #NCT01581125.

Keywords: appetite; circadian rhythms; endocrinology; fasting hormones; forced desynchrony; hunger; sleep loss; sleep restriction.

Figures

Figure 1

Raster plot of the Control (n = 7, 1:2 sleep:wake ratio, equivalent to 8 h sleep opportunity per 24 h day) and chronic sleep restriction (n = 8, 1:3.3 sleep:wake ratio, equivalent to 5.6 per 24 h day) forced desynchrony protocols. Clock hour is plotted on the horizontal axis and day of study on the vertical axis. Solid black bars represent sleep opportunities, yellow circles represent fasted blood draws, and the red dashed line represents the daily marker of a participant’s circadian period. Days are double plotted such that each consecutive study day is plotted next to and below the previous day.

Figure 2

Influence of circadian phase and sleep restriction on (A,B) subjective hunger, (C,D) leptin, and (E,F) ghrelin. The Control (n = 7, 1:2 sleep:wake ratio, equivalent to 8 h sleep opportunity per 24 h day) condition is denoted by open circles and the chronic sleep restriction (CSR, n = 8, 1:3.3 sleep:wake ratio, equivalent to 5.6 h sleep opportunity per 24 h day) condition by closed circles. Data are represented as raw scores (left) and z-scores (right) and double plotted across circadian phase and relative clock hour for an individual with a habitual sleep time of 2300–0700 hours. Error bars represent SEM.

Figure 3

Influence of circadian phase and sleep restriction on fasted (A,B) insulin and (C,D) glucose concentrations. The Control (n = 7, 1:2 sleep:wake ratio, equivalent to 8 h sleep opportunity per 24 h day) condition is denoted by open circles and the chronic sleep restriction (CSR, n = 7, 1:3.3 sleep:wake ratio, equivalent to 5.6 h sleep opportunity per 24 h day) condition by closed circles. Data are represented as raw scores (left) and z-scores (right) and double plotted across circadian phase and relative clock hour for an individual with a habitual sleep time of 2300–0700 hours. Error bars represent SEM.

Figure 4

Influence of circadian phase and sleep restriction on fasted (A,B) adiponectin and (C,D) cortisol concentrations. The Control (n = 7, 1:2 sleep:wake ratio, equivalent to 8 h sleep opportunity per 24 h day) condition is denoted by open circles and the chronic sleep restriction (CSR, n = 8, 1:3.3 sleep:wake ratio, equivalent to 5.6 h sleep opportunity per 24 h day) condition by closed circles. Data are represented as raw scores (left) and z-scores (right) and double plotted across circadian phase and relative clock hour for an individual with a habitual sleep time of 2300–0700 hours. Error bars represent SEM.