Racing heart at night: causes, when it is harmless and when to get help

Palpitations are the sensation of your heartbeat becoming more noticeable. The NHS describes them as usually harmless but worth getting help for if they keep happening or come with other symptoms. At night there are fewer distractions, you may be lying on your left side or with your ear on the pillow, and the house is quiet, so a heartbeat that you would not notice during the day can seem loud or fast.

Night is also when some real triggers cluster: a late coffee or alcohol, a big meal, anxiety that surfaces when you stop being busy, menopausal hot flushes and night sweats, and disrupted breathing in sleep. The cause is sometimes simply not enough sleep, which the NHS lists as a common trigger in its own right.

The NHS page on palpitations says common causes include strenuous exercise, lack of sleep, stress and anxiety, medicines (check the leaflet), and alcohol, caffeine, nicotine and recreational drugs. Sometimes palpitations are a sign of menopause, and some people get them in pregnancy. They can also be caused by iron deficiency anaemia, an overactive thyroid, a heart rhythm problem (arrhythmia) or other heart problems such as heart valve disease.

The NHS menopause page notes that hot flushes can cause palpitations or anxiety and that night sweats and sleep problems are common, so if you are in your forties or fifties and the racing heart arrives with sweats and broken sleep, that is a plausible link to raise with your GP.

• Anxiety or stress that is worse at bedtime, sometimes with a panic feeling on waking.

• Caffeine, alcohol or nicotine late in the day.

• Menopause or perimenopause with night sweats.

• An overactive thyroid, which the NHS says can cause palpitations, weight loss, heat sensitivity and difficulty sleeping.

• A rhythm problem such as atrial fibrillation or supraventricular tachycardia (SVT).

• Sleep apnoea, in which breathing repeatedly pauses in sleep.

Two rhythm problems the NHS describes are atrial fibrillation and SVT. With atrial fibrillation the heartbeat is not steady: it may feel like pounding, racing, fluttering, skipping or missing a beat, lasting seconds to minutes, and the heart rate may be faster than 100 beats per minute. It can come and go (paroxysmal) or be persistent. With SVT, the NHS says the heart suddenly beats much faster than normal, goes above 100 beats per minute, usually lasts a few minutes but can last several hours, and can be triggered by caffeine, alcohol or drugs though often there is no obvious trigger. Many people first have symptoms between 25 and 40 years old.

The NHS sleep apnoea page describes devices that check breathing and heartbeat overnight, and says untreated sleep apnoea can lead to high blood pressure, stroke, type 2 diabetes, heart disease and depression. If your partner notices loud snoring and pauses in your breathing, or you wake unrefreshed, mention it to your GP.

The NHS says to call 999 or go to A&E if you currently have palpitations that do not go away, or you also have chest pain, shortness of breath, or feel faint or you faint. If these symptoms have stopped, it says to ask your GP surgery for an urgent appointment, call 111 or get help from 111 online. It advises not driving yourself to A&E: ask someone to drive you or call 999, and bring any medicines you take.

For atrial fibrillation specifically the NHS lists chest pain, shortness of breath, sweating, feeling or being sick, fainting, a severe headache, weakness or numbness on one side of the face or body, blurred vision or loss of sight, and confusion or difficulty speaking as reasons to call 999 if you have a fast or irregular heartbeat at the same time. For SVT it says to call 999 if an episode lasts longer than usual or comes with shortness of breath, chest pain or feeling faint.

The NHS says to see a GP if palpitations keep coming back or happen more often, last longer than a few minutes, you have a heart condition, or there is a history of heart problems in the family. You may have an electrocardiogram (ECG), where small pads on the skin record the heart's electrical signals, and may be referred to a cardiologist. For atrial fibrillation, tests may include an ECG, echocardiogram, chest X-ray and blood tests.

Because night-time episodes may not happen while you are in the clinic, a heart monitor you wear for a day or more, or a device you activate when symptoms strike, may be used. Blood tests for anaemia and thyroid function are commonly part of the work-up because both are listed as causes. Keep a short diary of when episodes occur, what you had to eat and drink, and how long they lasted, and try to note your pulse if you can.

Treatment depends on the cause, and the NHS says palpitations often do not need to be treated. If they are not caused by a health condition, avoiding triggers such as stress, smoking, caffeine and alcohol can help. If a heart problem is the cause, you may need medicines or a procedure to help control the heartbeat.

Sensible steps include keeping caffeine and alcohol to the daytime and moderate amounts, avoiding large late meals, keeping a regular sleep routine, and looking at ways to unwind before bed. The NHS sleep apnoea page suggests losing weight if overweight, regular exercise, good sleep habits, sleeping on your side and avoiding sleeping pills unless recommended by a doctor. For SVT, the NHS says a doctor may recommend simple techniques to stop episodes, and that treatment in hospital can include medicines, cardioversion or catheter ablation if episodes are long or frequent.

On the NHS the GP can arrange blood tests and an ECG and refer to cardiology or to a rapid access service when appropriate. Waiting times for ambulatory monitoring vary by area.

Some people pay privately for a Holter monitor or a consultation with a cardiologist to be seen sooner. The tests are the same; make sure the results are shared with your GP, and remember that smartwatch readings, while interesting, should be taken to a clinician rather than relied on.