Fainting after waking up: what to know

After lying down for hours, standing quickly can briefly reduce blood flow to the brain. A full bladder, warm room, poor sleep, illness, dehydration, alcohol, or medicines that lower blood pressure can add to this effect. Warning signs include dizziness, weakness, nausea, sweating, muffled hearing and narrowing vision.

Other causes remain possible. Anaemia, Hypoglycaemia or an irregular rhythm such as Atrial Fibrillation can cause fainting or near-fainting. The timing after waking is useful information, but it does not establish the cause. A clinician will consider posture, symptoms, injuries, medical history and medicines.

Before standing, sit on the edge of the bed and move your ankles. Stand with support, pause, and sit or lie down at the first warning sign. Keep pathways clear, use a bedside light, and avoid walking alone to the bathroom while dizzy. Drink fluids during the day if your clinician has not restricted them.

If someone faints, lay them flat, raise the legs when practical, check breathing, and protect the head. Keep them under observation until fully alert. Do not offer food, drink or medicines while they are unconscious, and arrange assessment after recovery.

Call emergency services for delayed recovery, breathing difficulty, chest pain, severe headache, new weakness, confusion, seizure-like activity, a major injury or an irregular heartbeat. Fainting while lying down or without warning is particularly important to report urgently.

Seek prompt medical care after a first faint, after repeated episodes, or when there is heavy bleeding, persistent vomiting, poor intake or marked symptoms of Dehydration. Do not drive until the cause and safety plan have been discussed.

Ask whether posture-related blood-pressure testing, an ECG or blood tests are appropriate. Describe your waking position, warning symptoms, breakfast and fluid intake, medicines taken at night, palpitations, and any family history of sudden heart problems.