Figure 1.

An illustration showing the metabolic and sleep functions of leptin. (A) Leptin activates JAK-STAT pathways to decrease appetite and increase energy expenditure centrally. It also has important functions in reproductive health, glycemic control, and immune regulation. (B) Insufficient sleep and OSA can both influence leptin levels in the serum. Leptin, in turn, can reduce upper airway obstruction in sleep and improve sleep parameters such as sleep structure, quality, and duration. Leptin may also play a role in circadian rhythms. Abbreviations: JAK, Janus kinase; OSA, obstructive sleep apnea; STAT, signal transducer and activator of transcription.