Sleep fragmentation affects LDL-cholesterol and adipocytokines independent of food intake in rats

To explore biological mechanisms underlying the association between sleep fragmentation and hypercholesterolemia, we conducted an experimental study with 36 Wistar male rats aged 7 weeks. An experimental model for 4-day subchronic sleep fragmentation was applied to rats which were fed ad libitum or were given 50% restricted amount of standard chow. Sleep fragmentation was induced by a treadmill which moved intermittently for 3s with 30-second pauses between moves. Blood lipid and lipoprotein profiles and adiponectin, leptin, ghrelin, cortisol, epinephrine, and norepinephrine levels were compared among four groups including rats with ad libitum sleep and ad libitum intake (Control), those exposed to sleep fragmentation with ad libitum intake (SF), those with ad libitum sleep and diet restriction (DR), and those exposed to sleep fragmentation and diet restriction (SF+DR). SF and SF+DR showed a higher ratio of LDL and HDL cholesterol (184% and 132% increase, P-value for SF effects <0.001) and ghrelin (64% and 18% increase, P-value for SF effects <0.01) and lower leptin (76% and 44% decrease, P-value for SF effects <0.001) and adiponectin levels (3% and 18% decrease, P-value for SF effects <0.01) than Control. The LDL and HDL cholesterol ratio was highly correlated with leptin (rho = 0.92, P-value <0.001) and ghrelin (rho = 0.53, P-value <0.05) in Control and DR as well as with adiponectin (rho = 0.85, P-value <0.001) and leptin (rho = 0.60, P-value <0.01) in SF and SF+DR. Based on these findings, we suggest that sleep fragmentation may induce lipoprotein disturbances independent of food intake with decreased levels of adiponectin and leptin.