Can Cortisol help with sleep?

Cortisol is a stress hormone that follows a circadian rhythm: high in the morning to promote wakefulness, low at night to allow sleep. Elevated cortisol levels in the evening or at night are strongly associated with difficulty falling asleep, reduced deep sleep, and overall poor sleep quality. Conditions like Cushing's syndrome or chronic stress, which raise cortisol, often cause insomnia. Therefore, cortisol does not help with sleep; it is wake-promoting. Evidence: human-strong (circadian physiology, clinical studies). Caveat: Do not take cortisol supplements for sleep; instead, address stress and practice good sleep hygiene. Some research on very low-dose hydrocortisone for specific adrenal conditions exists, but that is medical, not general advice.