Heart palpitations when lying on your back

When you lie still, there is less background movement and noise, so a normal beat or occasional extra beat may feel stronger. Position can also alter pressure in the chest or abdomen, and a full stomach, reflux, stress, dehydration, caffeine, or poor sleep may add to awareness. Anaemia and iron deficiency anaemia can increase the heart's workload. Hyperthyroidism and anxiety can cause a fast pulse; atrial fibrillation may feel uneven. Heart failure is more concerning if lying flat brings breathlessness, coughing, ankle swelling, or waking suddenly short of breath. Position-related awareness alone cannot determine the cause.

Turn onto your side or sit up if that feels more comfortable, and check whether the sensation matches your wrist pulse. Keep a record of position, time, meals, stimulants, medicines, regularity, and breathlessness. Avoid heavy meals, nicotine, and excess caffeine close to bedtime. Arrange an appointment for repeated episodes, a new irregular pulse, or symptoms that limit sleep or activity.

Get emergency help for chest pain, fainting, severe breathlessness, blue lips, new confusion, sudden weakness, or a heartbeat that remains very fast or irregular with feeling unwell. Seek prompt assessment if you cannot lie flat because of breathlessness or symptoms are worsening over days.

Ask whether your pulse, blood pressure, medicines, hydration, blood sugar, thyroid function, or blood count should be checked. Mention the exact position or time of day, triggers, duration, and whether the beat felt regular.