Introduction

Stomach cancer, also known as gastric cancer, is a type of gastrointestinal (GI) cancer that develops when uncontrolled and abnormal cell growth occurs in the stomach. The stomach is a vital organ in the human digestive system. The digestive system breaks down food into smaller pieces for absorption for energy and growth. The stomach is found between the oesophagus and the small intestine.

The stomach lining has five layers, and all are susceptible to stomach cancer. The most common types of stomach cancer are adenocarcinomas, originating from the gland cells in the innermost lining of the stomach. Less common forms of stomach cancer include lymphomas and gastrointestinal stromal tumours (GISTs). When abnormal cells accumulate in the stomach, they form a tumour and can metastasise, where they spread to other parts of the body. 

Sleep is essential for maintaining health as it allows the body to rest and preserve the function of the immune system. Research suggests that there is a potential link between quality of sleep and gastrointestinal cancers, including stomach cancer.¹ Sleep problems may increase the risk of developing certain cancers. They may also influence how cancer progresses and how effective cancer treatments are. Improving one’s sleep may aid in coping with cancer treatment and recovery.

Stomach cancer overview

Types of stomach cancer

The type of stomach cancer someone has depends on the type of cell where the tumour originated. The main types of stomach cancers are:

• Adenocarcinomas – makes up 90-95% of stomach cancers and affects the innermost lining of the stomach
• Gastrointestinal stromal tumours (GISTs) – develop in the interstitial cells of Cajal that comprise the stomach wall
• Carcinoid tumours – cancer that develops in neuroendocrine cells, which function in the nervous system and in hormone production
• Lymphoma – cancer within immune cells
• Other cancers – small cell carcinomas, squamous cell carcinomas, and leiomyosarcomas can start in the stomach but are infrequent

Prevalence

The rate of stomach cancer has declined over recent decades in most parts of the world. It is uncommon in the UK.² Globally, stomach cancer is the fifth most common cancer,³ with the highest occurrences in East Asia.² Stomach cancer is more common in people assigned male at birth (AMAB) than in people assigned female at birth (AFAB).²

Risk factors

The cause of stomach cancer is unknown, although there are risk factors that increase the chances of developing it, namely:⁴

• Having a diet lacking in fruits and vegetables
• Having a diet high in salty and smoked foods
• Smoking
• Gastritis – swelling and irritation of the stomach
• Polyps – benign, non-cancerous growths in the stomach
• Bacterial infections in the stomach caused by the bacteria Helicobacter pylori (H. pylori)
• Gastro-oesophageal reflux disease (GORD), or acid reflux occurs when stomach contents back up into the oesophagus
• Familial history of stomach cancer or genetic conditions that increase cancer risk
• Genetic mutations in the CHD1 gene

Symptoms

It is difficult to detect early-stage stomach cancer, as there are usually no noticeable symptoms present. However, as stomach cancer progresses, people may experience the following observable symptoms:

• Heartburn or acid reflux
• Bloating – feeling full even after consuming small amounts of food
• Difficulty swallowing (dysphagia)
• Abdominal pain – unexplained pain or discomfort in the abdomen
• Unintended weight loss – accompanied by loss of appetite, trouble eating, or nausea
• Nausea and vomiting – including vomiting blood 
• Bloody or black stools

Sleep and health

Sleep plays a crucial role in preventing cancer, far beyond simply resting the body. It supports the immune system by enhancing the function of white blood cells and natural killer (NK) cells, which help remove abnormal cells before they grow into tumours. In fact, chronic sleep disruption or insufficient sleep can reduce melatonin, a hormone that helps regulate sleep and has natural anti‑cancer properties including DNA protection and suppression of tumour growth.

Disturbance to our internal clock, or circadian rhythm, reduces melatonin and causes inflammation and DNA damage, conditions linked to cancer onset.¹ One study found that both too little (≤5 hours) and too much sleep (≥9 hours) dramatically raise the odds of developing gastric cancer by around 1.3 and 2.0 times, respectively.⁶ 

The two stages of sleep are:

• NREM (non-rapid eye movement) sleep
• REM (rapid eye movement) sleep

NREM sleep occurs in three increasingly deepening stages with the third stage being the deepest. NREM sleep is key for physical and mental restoration. Sleep deprivation or interrupted sleep can decrease NREM sleep and this can lead to health problems such as impaired physical healing and mental health issues. REM is the fourth and final stage of sleep. It is important for dreaming, forming memories, processing emotions, and brain development.

Impact of stomach cancer on sleep

Undergoing treatment for stomach cancer can adversely affect one’s sleep. Factors that interfere with sleep include pain and discomfort, emotional stress and cancer treatment side effects such as nausea. This can negatively affect one’s quality of life and prognosis. Cancer survivors similarly report experiencing trouble sleeping or insomnia.

Stomach cancer can interfere with sleep through a myriad of ways: 

• Pain from a tumour or cancer treatment
• Fever or infection due to reduced immune system function caused by chemotherapy
• Discomfort or pain from digestion issues due to a tumour or cancer treatment
• Side effects from medication
• Stress and anxiety post diagnosis
• Disrupted sleep from fatigue and daytime napping

Lack of sleep or poor quality sleep from symptoms of stomach cancer can cause:

• Fatigue
• Difficulty with concentration
• Headaches
• Irritability
• Insomnia
• Disrupted sleep patterns
• Daytime sleepiness and napping
• Stress and anxiety due to diagnosis and treatment
• Other side effects related to treatment: pain, nausea, weight gain, hormonal changes

Additionally, poor sleep quality can contribute to other health issues such as sleep apnoea, diabetes and depression. Health conditions like diabetes and depression affect the body’s metabolism and are separate risk factors for cancer themselves.⁷

The role of sleep in cancer recovery

Sleep and the immune system

Cancer treatments often suppress white blood cell production, weakening immune defence against infection. Quality sleep is essential to restore immune function, enabling the production of immune cells that can also target cancer cells.

Sleep and treatment effectiveness

A good night’s sleep helps regulate stress hormones, balance mood, and may enhance responsiveness to treatments such as chemotherapy, radiotherapy and immunotherapy. Melatonin specifically supports immune response and may strengthen treatment outcomes.

Sleep and recovery

Adequate sleep offers several benefits in the recovery phase of cancer treatment:

• Faster healing and reduced post‑surgery complications 
• Greater pain tolerance
• Improved mental alertness, mood, and quality of life 
• Lower risk of long‑term effects such as prolonged fatigue, depression, and metabolic disorders 

Good quality sleep is vital at all stages, from preventing cancer to managing symptoms, increasing treatment success, and aiding recovery. It supports immunity, hormone balance, emotional resilience, and physical healing. Conversely, poor sleep worsens several risk factors and symptoms related to stomach cancer.

Sleep management during stomach cancer

Getting quality sleep and the right amount of sleep can be difficult for people with stomach cancer and those undergoing stomach cancer treatment. Different strategies can help with sleep management during stomach cancer or treatment: lifestyle changes, medical interventions, psychological support and relaxation techniques.

Lifestyle changes to improve sleep

Aside from medication, a variety of lifestyle changes can improve sleeping patterns, such as:

• Develop a consistent and stable sleep routine – create comfortable and relaxing conditions. Consider taking a hot bath or reading a book before bedtime to ready oneself for sleep
• Sleep in a quiet place with no or minimal light 
• Utilise comfortable sleeping positions, using accessories such as pillows
• Avoid exercising before sleeping
• Avoid caffeine, alcohol and tobacco
• Limit screen time prior to sleeping

Medical interventions for sleep issues

If you experience insomnia or difficulty sleeping, your doctor may be able to prescribe medication to attenuate the pain and potentially improve your quality of sleep:

• For mild pain – over-the-counter medications such as aspirin or ibuprofen
• For moderate to severe pain – prescription painkillers of varying strength 
• For insomnia – sleeping supplements such as melatonin

Psychological support and relaxation techniques

Psychological support and relaxation techniques may provide some relief from stress and anxiety causing sleep problems. Effective practices that can provide some mental relief include:

• Meditation or yoga and regularly practicing mindfulness throughout the day and all activities 
• Listening to soothing music or reading a book
• Seeking emotional support from a close friend or family member
• Individual counselling sessions 
• Participating in peer support groups and programmes aimed at those suffering from chronic anxiety
• Therapies such as CBT-I (Cognitive Behavioral Therapy for Insomnia)

Summary

Stomach/gastric cancer denotes when abnormal cell growth occurs in the stomach. Sleep is vital in maintaining the body’s healing and functioning immune system to combat diseases. Research suggests there is a relationship between sleep interference and increased cancer risk. Stomach cancer and its treatments can negatively impact sleep, which in turn reduces the body’s ability to cope with stress and fight infection and cancer. Improving sleep can strengthen the immune system and increase cancer treatment and recovery. Lifestyle changes, medical interventions, and psychological support can help someone better manage sleep issues when dealing with stomach cancer. Talk with your doctor if you are experiencing sleep problems related to stomach cancer so you can access the support you need.