100F heat can block the body’s usual 2-3 degree nighttime temperature drop, experts said, making it harder to fall asleep because melatonin release and the brain’s sleep-prep signals are disrupted.
Humidity compounds the problem by weakening sweating and skin-cooling, while clock-watching, frustration and catastrophizing activate the sympathetic nervous system and adrenaline, keeping people awake longer.
Sleep specialists advised cooling the bedroom first—close blinds by day, use the lowest floor, open windows only when air cools, and choose light cotton or linen bedding, loose sleepwear, fans or brief cold fabrics.
Alcohol, caffeine, heavy meals, late vigorous exercise and large amounts of water right before bed can all worsen hot-night sleep, even though hydration still matters during heat.
Older adults, infants, young children and pets face higher heat risk; experts urged checking for confusion, trouble waking, stopped sweating or very high body temperature—signs that need emergency care.