The science of insomnia: how it works and how sleep medicine treats it.

Onset insomnia is most often a problem of cortical arousal at the sleep-wake threshold. The systems that should be ramping down (sympathetic tone, cortical attention, the hypothalamic alerting signal) are still up. Melatonin timing can be misaligned, and the GABA-driven sedation that closes out the day is not engaging cleanly. The treatments that target this pattern are different from the ones that treat early waking.

Maintenance insomnia typically reflects a problem of sustained sleep. Histamine and orexin signaling reactivate during the second half of the night, and cortisol begins its morning ramp earlier than it should. The brain effectively wakes itself up and cannot get back under. Selective histamine-1 antagonism at low doses is one of the mechanisms specifically validated for this pattern.

Early-morning waking is often a circadian-phase issue layered with a sustained-sleep failure. The internal clock has advanced. The body is preparing for morning too early, and the sleep-stabilizing systems cannot hold against it. Treatment here is about both phase correction and maintaining sleep architecture through the second half of the night.

Non-restorative sleep is an architecture problem rather than a duration problem. Slow-wave sleep is fragmented, REM cycles are shallow or interrupted, and micro-arousals are not visible to consciousness but are very visible to a recovery score. Pattern work here often begins with a home sleep test to rule out sleep-disordered breathing before any medication conversation.