Orexin & Wake Stability
topic
Orexin (hypocretin) is a neuropeptide produced in the lateral hypothalamus that promotes and stabilizes wakefulness — preventing inappropriate transitions into sleep by maintaining arousal-system tone — with deficiency producing narcolepsy (sudden sleep attacks and cataplexy). Its secretion is driven by activity, light exposure, and emotional arousal, and its suppression at night contributes to the sleep-facilitating effect of evening darkness and physical relaxation.
Role
Orexin system understanding explains why afternoon inactivity, dim evening light, and thermal comfort facilitate sleep onset — they reduce the inputs that sustain orexin-driven wakefulness — and why the bright, socially stimulating, physically active evening of modern urban life systematically defeats the biological sleep-onset process. The evening behaviors that most people treat as neutral (bright overhead lighting, exciting screen content, stimulating social media) are, through their effect on the orexin system, active interventions against the neurochemical conditions required for natural sleep onset.