Hypothyroidism and heart palpitations at night

An underactive thyroid more often causes a slower body pace, fatigue, cold intolerance, constipation, daytime sleepiness, or generalised weakness. Palpitations can instead relate to an abnormal heart rhythm, stress, caffeine, dehydration, fever, anaemia, or an overactive thyroid. They may also occur if thyroid replacement is more than your body needs. Noticing the sensation at night does not by itself identify the cause; recording its timing, duration, rhythm, and associated symptoms can help a clinician.

Book a medical review if palpitations recur, wake you, or feel irregular. Do not stop or change thyroid medicine without advice. Bring the dose, timing, other medicines, supplements, and a list of triggers such as caffeine or nicotine. A clinician may check your pulse, perform an electrocardiogram, and order thyroid or other blood tests. Until reviewed, limit known triggers, drink fluids normally, and note whether the heartbeat feels fast, pounding, fluttering, or skipped.

Get emergency help for palpitations with chest pain, severe breathlessness, fainting, new confusion, or collapse. Seek urgent assessment for a sustained very fast or irregular heartbeat, especially with dizziness or weakness. If episodes are brief but continue to recur, arrange prompt primary-care review rather than assuming hypothyroidism explains them.

Could my thyroid dose or another medicine be contributing? Do I need an electrocardiogram or rhythm monitoring? Which thyroid results should be checked, and when? Which symptoms mean I should seek emergency help?