Heat exhaustion and sleep: what to know

Heat exhaustion develops when sweating and heat exposure leave the body struggling to regulate temperature and replace lost fluid and salts. You may feel drained yet unable to settle, wake with thirst, or notice a headache, dizziness and heavy sweating. Fatigue can continue after you leave the hot setting. Sleep itself does not treat the underlying fluid loss, so waking feeling worse, confused or unable to drink needs attention. See [Heat Exhaustion](/conditions/heat-exhaustion/) and [Dehydration](/conditions/dehydration/) for related explanations.

Move to an air-conditioned or shaded place, loosen extra clothing and use cool, damp cloths on the skin. Sip water or an oral rehydration drink if you are awake and can swallow; avoid alcohol. Rest quietly and avoid exercise or more heat until you feel recovered. Keep the room comfortably cool and ask someone to check on you if you felt faint. [Excessive Sweating](/symptoms/excessive-sweating/) and [Excessive Thirst](/symptoms/excessive-thirst/) can help you recognise ongoing fluid loss.

Get urgent help if the person becomes confused, faints, has a seizure, cannot drink, vomits repeatedly, has trouble breathing, or remains very hot and unwell after cooling. Emergency assessment is also needed if symptoms are worsening rather than easing. Do not give fluids to someone who is not fully alert. A persistent [Dizziness](/symptoms/dizziness/) or [Headache](/symptoms/headache/) after cooling deserves medical advice.

Ask whether your symptoms fit heat exhaustion, how much rest is sensible, when you can return to work or exercise, and whether medicines or a health condition increase your heat risk.