Sleep is increased by weight gain and decreased by weight loss in mice.
OBJECTIVE
To determine whether weight loss could reverse excessive sleep in high-fat diet-induced obesity.


METHODS
Three groups of mice participated in the study. A weight gain/loss group was fed with high-fat food for 6 weeks (weight gain), and regular food again for 4 weeks (weight loss). A control group and a weight gain only group were fed with regular food and high-fat food, respectively, for 10 weeks after the baseline.


METHODS
Adult male C57BL/6 mice.


METHODS
The amounts of wake, rapid eye movement sleep (REMS) and non-REM sleep (NREMS) were determined at week 0 (baseline), week 6, and week 10.


RESULTS
The weight gain/loss group displayed a significant decrease in wakefulness and increases in NREMS and episodes of NREMS during 6 weeks of weight gain, which were reversed during subsequent 4 weeks of weight loss. The weight gain only group displayed significant decrease in wakefulness and increase of NREMS and REMS at both week 6 and week 10. The control group did not show significant sleep alterations during the experiment.


CONCLUSIONS
These observations indicate that sleep alterations induced by weight gain are reversed by weight loss in obese animals. These data may shed light on the mechanisms underlying the well-established association between obesity and sleepiness in humans and may lead to new therapeutic strategies for these 2 increasingly prevalent problems in the modern societies.
Department of Psychiatry, Pennsylvania State University College of Medicine, Hershey, PA 17033, USA.
Zhiwei
Z
Guan
Alexandros N
AN
Vgontzas
Edward O
EO
Bixler
Jidong
J
Fang
D000818:Animals; D002540:Cerebral Cortex / Q000503:physiopathology; D004041:Dietary Fats / Q000008:administration & dosage; D004569:Electroencephalography; D004576:Electromyography; D002149:Energy Intake / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D005583:Fourier Analysis; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009765:Obesity / Q000503:physiopathology; D012815:Signal Processing, Computer-Assisted; D012890:Sleep / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology; D015430:Weight Gain / Q000502:physiology*; D015431:Weight Loss / Q000502:physiology*
D004041:Dietary Fats