Fainting in your sleep: what to know

Details can help a clinician distinguish events: jerking, tongue biting, loss of bladder control, prolonged confusion, unusual breathing, palpitations, or injury are relevant. Anaemia, dehydration, and hypoglycaemia may also make a person faint or become confused, while Atrial Fibrillation may cause an irregular heartbeat and reduced blood flow. These conditions cannot be diagnosed from the timing alone.

Check whether the person responds and is breathing normally. If they are breathing, place them on their side if they are drowsy or vomiting, protect them from nearby hazards, and stay with them. Do not restrain movements or put food, drink, or objects in their mouth. Note the start and end time, movements, skin colour, breathing, and recovery, and arrange medical review.

Call emergency services if breathing is abnormal, the person cannot be woken, the event lasts longer than expected, another episode follows, or there is chest pain, severe injury, confusion, new weakness, or a severe headache. Seek urgent assessment for a first event, an episode during pregnancy, or a known heart condition. Do not let the person drive until reviewed.

Ask which features suggest fainting, a seizure, or a rhythm problem; whether an electrocardiogram, glucose check, blood tests, or specialist assessment is needed; and what activity restrictions apply. Bring the witness account and any video recorded safely from a distance.