Lack of sleep reduces insulin sensitivity, fat oxidation in postmenopausal women

Sleep restriction for four nights results in decreased insulin sensitivity and fat oxidation among postmenopausal women, a study has shown.

A group of researchers examined the effect of sleep restriction on insulin sensitivity and energy metabolism in this randomized crossover trial. Fourteen women went through four nights of habitual sleep (HS: 100-percent normal sleep) and sleep restriction (60 percent of HS), while on a eucaloric diet.

Outcomes measured were as follows: insulin sensitivity by hyperinsulinemic-euglycemic clamp, defined as the glucose infusion rate (GIR); resting metabolism and substrate oxidation by indirect calorimetry; and glucose, insulin, and C-peptide concentrations following a standard meal test.

Of the participants, nine were included in the final analysis. Their mean age was 59 years, and their mean body mass index was 28.0 kg/m². Accelerometer-determined total time in bed was 8.4 hours during HS relative to 5.0 hours during sleep restriction (38-percent reduction; p<0.0001).

Compared with HS, sleep restriction led to a 20-percent reduction in low-dose insulin (2.55 vs 2.03 mg/kg/min; p=0.01) and a 12-percent decrease in high-dose insulin GIR (10.48 vs 9.19 mg/kg/min; p<0.001). In addition, sleep restriction reduced fat oxidation during high-dose insulin infusion (p<0.01) and did not change the resting energy metabolism.

“These findings underscore the role of insufficient sleep in metabolic dysfunction following menopause,” the researchers said. “Larger trials investigating how sleep disturbances cause metabolic dysfunction during menopause are needed across all stages of menopause.”