Influence of Partial Sleep Deprivation on Energy Balance and Insulin Sensitivity in Healthy Women

Well-controlled laboratory studies in healthy adults have shown that repeated partial sleep restriction adversely affects systemic insulin sensitivity and glucose tolerance.

“well-controlled laboratory studies in healthy adults have shown that repeated partial sleep restriction has adverse effects on systemic insulin sensitivity and glucose tolerance”

The finding identifies a molecular mechanism that may be involved in the reduction in total body insulin sensitivity observed in multiple laboratory studies of partial sleep deprivation.

“To our knowledge, this finding identifies for the first time a molecular mechanism that may be involved in the reduction in total body insulin sensitivity consistently observed in multiple laboratory studies of partial sleep deprivation in healthy adults (11–17), as well as in the participants of our study.”

Experimental sleep restriction promotes a positive energy balance by affecting leptin and ghrelin, increasing hunger and appetite, increasing caloric intake, decreasing caloric expenditure, and increasing body weight.

“Experimental sleep restriction also promotes a positive energy balance by affecting levels of the hunger regulating hormones leptin and ghrelin;27 increasing hunger and appetite,27 with particular cravings for fat and sweet and salty snacks;27,28 increasing caloric intake;27,67 decreasing caloric expenditure through physical activity;68 and increasing body weight.28,67,69”

One study showed an increase of 0.4 kg in body weight in women as sleep was progressively restricted from more than 8 hours per night at baseline to 4 hours per night over 4 nights.

“One study57 showed an increase of 0.4 kg in body weight in women as sleep was progressively restricted from >8 h/night at baseline to 4 h/night over 4 nights”

Studies examining resting metabolic rate using indirect calorimetry found either no difference or a lower resting metabolic rate with sleep restriction relative to habitual sleep.

“Studies that have examined the impact of sleep duration on resting metabolic rate using indirect calorimetry have found either no difference57,62,79–81 or a lower resting metabolic rate69 with sleep restriction relative to habitual sleep.”

Sleep restriction generally increases 24-hour energy intake relative to habitual sleep, with overeating ranging from about 180 to 559 kcal per day.

“In general, studies reported increases in 24-hour energy intake when participants underwent sleep restriction relative to habitual sleep (Table 1), with the degree of overeating ranging from ≈180 to 559 kcal/d.”

Subsequent studies have found mixed results regarding leptin, with some showing elevations as opposed to decreases in leptin levels following sleep restriction and others showing no changes.

“Subsequent studies have found mixed results regarding leptin, with some showing elevations as opposed to decreases in leptin levels following sleep restriction [74][75][76][77] and others showing no changes.77,78”

Three studies found no alterations in measures of glucose metabolism.

“Conversely, three studies [11, 145, 217] found no alterations in measures of glucose metabolism.”

Bosy-Westphal et al. reported a 0.4 kg weight gain in freely living lean, overweight, and obese women after four nights of about 5.5 h sleep compared with two nights of about 9 h sleep.

“Bosy-Westphal et al. reported a weight gain of 0.4 kg in a group of freely living lean, overweight, and obese women after four nights of ~5.5 h of sleep in comparison to two nights of ~9 h of sleep [11].”

Because leptin is increased by food intake and correlates with obesity, the unchanged or increased leptin levels may be the expected consequence of the positive energy balance from greater food intake and weight gain.

“As leptin levels are enhanced by food intake and correlate with the degree of obesity [25], these latter results may be the expected consequence of the positive energy balance achieved by increased food intake [11, 116, 146] and weight gain [11, 116].”

In young women given an ad libitum diet, four nights of about 5.5 h sleep versus two nights of about 9 h produced a 20% increase in self-reported food consumption during sleep restriction.

“When young women were exposed to an ad libitum diet during two bedtime conditions, i.e., four nights of ~5.5 h of sleep vs. two nights of ~9 h of sleep, a 20% increase in self-reported food consumption was observed during sleep restriction [11].”

Four studies with ad libitum food access before or during leptin assessment found unchanged or increased leptin after sleep restriction.

“The four studies that provided ad libitum food access prior to or during leptin assessments found unchanged or increased leptin levels after sleep restriction [11, 116, 146, 154].”

St-Onge et al. found an increase of about 300 kcal/day after five days of 4 h bedtimes despite no clear effect on subjective hunger and appetite, suggesting that subjective assessments are unreliable.

“Of note, the study of St-Onge et al. reported an increase of ~300 kcal/day after 5 days of 4 h bedtimes, although there was no clear effect of sleep duration on subjective feelings of hunger and appetite on the previous day [11, 170], suggesting that subjective assessments are unreliable.”

In the only study focusing on women only, progressive sleep curtailment over 4 nights had no impact on measures of glucose tolerance and insulin sensitivity.

“In the only study focusing on women only, no impact of progressive sleep curtailment over 4 nights was reported on measures of glucose tolerance and SI [28].”

In young women, 4 nights of about 5.5h sleep versus 2 nights of about 9h sleep with an ad libitum diet increased self-reported food consumption by 20% and produced weight gain of 0.4 kg.

“when young women were exposed to an ad libitum diet during 2 bedtime conditions, ie 4 nights of ∼ 5.5h of sleep vs. 2 nights of ∼ 9h of sleep, a 20% increase in self-reported food consumption was observed in the sleep restriction condition and weight gain (+0.4kg) occurred [28].”

Bosy-Westphal et al. found no change in resting energy expenditure after 4 nights of approximately 5.5h in bed compared to a rested condition, even when adjusted for fat-free mass or total EE.

“Bosy-Westphal et al. studied 14 healthy lean and obese women after 4 nights of ∼ 5.5h in bed, by indirect calorimetry; compared to the rested condition (∼9h sleep for 2 nights), there was no change in resting EE, even when adjusted for fat-free mass or total EE [28].”

Partial sleep deprivation of 5 hours in bed for one week in men and 4 days of decreasing sleep curtailment in women also observed decreased insulin sensitivity and glucose tolerance.

“In other studies that enforced partial sleep deprivation (5 hours in bed) for one week in men [24] and 4 days of decreasing sleep curtailment (7 hours, 6 hours, 4 hours, 4 hours on consecutive nights) in women [25] also observed decreased insulin sensitivity and glucose tolerance.”

The effects of sleep restriction on leptin levels in subsequent studies have been mixed, with some studies reporting an increase and others reporting no significant difference after sleep restriction.

“The effects of sleep restriction on leptin levels in subsequent studies have been mixed, with some studies reporting an increase in leptin [25, 41–45] while others reported no significant difference [33, 46–51] after sleep restriction.”

In 14 healthy women, 4 nights of consecutively increasing sleep curtailment with an ad libitum diet had a profound effect on total energy intake (+20%, p<0.05) with no changes in energy expenditure.

“In 14 healthy women (BMI: 20.0–36.6 kg/m2), 4 nights of consecutively increasing sleep curtailment (7 h, 6 h, 6 h and 4 h sleep/night) with an ad libitum diet had a profound effect on total energy intake (+20%, p<0.05) with no changes in energy expenditure [25].”