What role does SHBG play in sleep?

The role of SHBG (sex hormone-binding globulin) in sleep is not yet fully understood. SHBG binds sex hormones like testosterone and estradiol, regulating their bioavailability. Since sex hormones can influence sleep-wake cycles—for example via effects on the hypothalamic-pituitary-gonadal axis—SHBG may indirectly modulate sleep quality. Low SHBG levels are associated with metabolic disturbances such as insulin resistance and obesity, which in turn predispose to sleep apnea and disrupted sleep. Some studies suggest a link between low SHBG and shorter sleep duration or poorer sleep efficiency, but effect sizes are small and evidence is mixed. The provided context (rs4880, rs35333999) pertains to antioxidants and PER3, respectively, and does not directly address SHBG. Therefore, the evidence for a direct role of SHBG in sleep is weak to moderate. No clinically actionable conclusions can be drawn at this point. Further research is needed to confirm causal mechanisms.