Heartburn is a common symptom that occurs due to acid reflux. When acid moves up from the stomach into the food pipe (oesophagus), it causes irritation and inflammation. People complain of a burning sensation behind their breastbone. If acid reflux happens repeatedly, it is known as gastroesophageal reflux disease (GERD/GORD).

Heartburn often worsens at night. It can prevent individuals from going to sleep and cause significant discomfort. Considering around 20% of people suffer from GERD, tackling nighttime symptoms is crucial.

Other GERD symptoms include difficulty swallowing (dysphagia), regurgitation of food or sour liquid, a sensation of a lump in the throat (globus), chronic cough, and a hoarse voice.

Why Does Heartburn Occur at Night?

Heartburn occurs when acid rises out of the stomach and up into the oesophagus. Nighttime acid reflux (or nocturnal gastroesophageal reflux) is extremely common. Some people only experience acid reflux at night.

It can happen for several reasons, including eating large meals late in the evening, lying flat in bed, or sleep problems such as obstructive sleep apnoea.

One of the biggest issues is lying flat. During the day, gravity helps reduce reflux by preventing acid from travelling upwards out of the stomach. However, when you lie flat, these beneficial effects of gravity are gone. The acid is no longer pulled downward, making it easier to enter the oesophagus.

What Causes Heartburn at Night?

The causes of heartburn at night are largely the same as during the day. Heartburn occurs either due to excessive acid production or a weakening of the lower oesophageal sphincter (LOS/LES) that normally acts as a valve between the stomach and oesophagus.

Other causes of heartburn at night include:

Eating Too Close to Bedtime

Gravity is only one factor. Eating a large meal near bedtime, then lying flat, can exacerbate the problem. A large meal increases the pressure in your stomach, making it easier for the LES to open. When you lie flat, the acid is then pushed upwards.

Top tip: Avoid eating 2-3 hours before bed.

Trigger Foods

Certain foods can stimulate acid production or weaken the LES. Eating these foods can increase the risk of acid reflux, especially at night. Common trigger foods include:

• Spicy foods

• Fatty or fried foods

• Citrus fruits (oranges, lemons, grapefruit)

• Tomatoes and tomato-based sauces

• Chocolate

• Carbonated drinks

• Peppermint

• Onions and garlic

• Alcohol

Drinking Alcohol or Caffeine in the Evening

Alcohol and caffeine both relax the LES and stimulate acid production. You might not think much about a small glass of wine or an evening cup of coffee. However, the effects of caffeine can linger in your system for several hours and may increase nighttime reflux.

Slow Digestion

As you sleep, your digestion slows. This means the food in your stomach stays there for longer, increasing the chance for acid to head back up your oesophagus.

Presence of Sleep Breathing Issues

Obstructive sleep apnoea (OSA) is a condition where people have moments where they don’t breathe during their sleep. OSA raises the pressure in your chest and can suck acid up into the oesophagus. This acid, in turn, worsens apnoea, leading to a negative feedback cycle.

Sleep Position

Gravity is a friend and an enemy. Lying completely flat allows acid to pool in the oesophagus. But the reverse is also true. By propping yourself up at an angle of 15-30° can decrease the severity or prevalence of acidity attacks.

Sleeping on your right-hand side also worsens attacks, whereas sleeping on your left-hand side can help prevent them.

Obesity or Pregnancy

Obesity and pregnancy increase the pressure in your abdomen. When lying flat, they press upon the stomach, forcing the contents into the oesophagus. Pregnancy also releases hormones that relax the LES. Together, the increased pressure and relaxed LES make acid attacks more likely to occur.

Medications

People often take their medications at night. Unfortunately, some medications can worsen acid reflux symptoms, leading to nighttime attacks. Common culprits include:

• Calcium channel blockers (blood pressure medication)

• Muscle relaxants

• Sedatives or sleep aids

• NSAIDs (e.g., ibuprofen or naproxen)

Treatments for Heartburn at Night

Dealing with heartburn at night isn’t difficult. By changing your underlying habits, you might prevent your symptoms. Try these tips:

• Avoid late meals — stop eating 2–3 hours before bedtime to reduce pressure in the stomach.

• Limit trigger foods — especially spicy, fatty, or tomato-based foods, and citrus fruits, chocolate, peppermint, and carbonated drinks.

• Reduce evening alcohol and caffeine — both weaken the LES and increase acid production.

• Elevate the head of your bed — raising it by 15–30° or using a wedge pillow helps prevent reflux when lying down.

• Sleep on your left side — this position reduces reflux episodes; avoid sleeping on the right side.

• Use over-the-counter medications — antacids for quick relief; H2 blockers or PPIs to lower acid production.

You might also want to address contributing factors such as obesity, sleep apnoea, or medications. If your symptoms persist despite these changes, seek medical attention.

Nighttime heartburn is exhausting and disruptive. The lack of sleep exacerbates symptoms and leaves you struggling to feel well-rested. Book a reflux assessment with The Functional Gut Clinic to find the cause and get personalised treatment.