Updated at: 06-01-2022 - By: Jane Brody

In terms of public health, cancer is a big issue. Around 21% of men and 18% of women will be diagnosed with cancer at some time in their lives, according to estimates. As the population grows and ages, these numbers are only anticipated to get worse.

A cancerous tumor develops when cells expand uncontrollably and spread to nearby healthy tissue. Rather than being a single disease, there are various varieties of cancer, each with its own unique causes, symptoms, and effects on the body.

Many sleep researchers are now focusing on the link between sleep and cancer because of the growing understanding of the importance of sleep in general health.

Despite the fact that additional research is required, specialists have discovered a complex connection. An inability to get a good night’s sleep has been linked to an increased risk of some cancers. It’s possible that they have an impact on how quickly cancer spreads and how well the treatment works.

Cancer can also disrupt your sleep. A patient’s quality of life might be negatively affected by sleep issues caused by cancer symptoms or medication side effects. The physical and mental effects of cancer can remain even after treatment has ended, and this can make it difficult for cancer survivors to sleep.

Finding understanding how cancer and sleep are intertwined can lead to better health outcomes. The risk of cancer cannot be completely eliminated, however, having adequate sleep may be a preventative factor. People with cancer may benefit from greater sleep in terms of both physical and emotional well-being, allowing them to better cope with the disease.

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Can Sleep Affect Cancer?

It’s well-known that getting enough sleep is essential for good health. As sleep affects practically every function in the body, research points to a variety of ways in which it may influence cancer.

The brain, immune system, synthesis and regulation of hormones, metabolism, and body weight may all be affected by sleep in ways that affect cancer risk. It is possible that sleep alters the environment in which cells operate and the signals that control how they grow.

In spite of the fact that this field of study is still developing, the following sections present an overview of the most recent findings in this area.

Concerned individuals should seek the advice of their physician to see how this information pertains to their own circumstances.

Sleep and Cancer Risk

There is growing evidence that sleep length, quality, circadian rhythm, and sleep disorders all impact cancer risk. Nevertheless, research on this topic is not always consistent or conclusive, which may reflect the difficulty in accurately collecting long-term data concerning sleep.

Sleep Duration

Many studies on the link between sleep length and cancer risk are inconclusive. Disparities between studies could be explained by differences in how sleep data is gathered, types of cancers studied and other risk variables are taken into account.

The chance of death from any cause is higher for people who sleep less than six hours a night, and a recent study indicated that persons with short sleep have a higher cancer risk as well.

Having a short sleep duration has been linked to an increased chance of developing colon polyps, which can then progress to cancer. Reduced sleep in the elderly has been linked to an increased risk of stomach cancer and Non-Hodgkin Lymphoma, as well as thyroid, bladder, and head and neck malignancies.

These investigations, however, are not conclusive. Short sleep has not been found to affect several cancer types, including lung cancer, in other research. People who sleep less than seven or eight hours per night may even be at a lower risk of developing cancer, according to some studies.

A lack of sleep has been linked to an increase in “wear and tear” on cells, which could lead to DNA damage that can lead to cancer in animals. In theory, sleep and cancer may be linked, despite the lack of conclusive human studies on the subject.

In addition, sleep deprivation may raise the risk of cancer. Obesity is a known risk factor for a wide range of cancers, and insufficient sleep has been related to obesity. Poor sleep may increase one’s risk of developing immune system problems such as chronic inflammation.

Long sleep duration, which is typically described as sleeping more than nine hours each night, has also been linked to an increased risk of cancer. One study indicated that older persons who had less sleep, especially those who were overweight or snored a lot, had a higher chance of developing colorectal cancer. Primary liver cancer and breast cancer, particularly the estrogen-driven subtype, have been linked to longer sleep duration.

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Sleep Quality

Long-term studies may have a harder time determining the impact of sleep quality on cancer risk since it is more difficult to correctly quantify than a duration of sleep.

Tumor growth and progression were accelerated in mice whose sleep was disrupted. Research of more than 10,000 adults over the age of 50 indicated an increased risk of cancer in those who reported having an intermediate or poor quality of sleep.

An additional study of nearly 4,000 women discovered a link between insomnia and the severe form of breast cancer known as triple-negative. Prostate cancer was found to be more prevalent in males who experienced sleep disturbances, with the greatest risk found in those with the most severe sleep disturbances.

More research is needed to reproduce and verify these findings, just as there is for sleep length. Future studies may provide light on how specific aspects of sleep quality, such as the frequency or length of sleep disruptions, increase the risk of getting certain forms of cancer.

Circadian Rhythm

The body’s internal clock, the circadian rhythm, is a 24-hour cycle. Depending on the time of day, signals from the suprachiasmatic nucleus (SCN) in the brain direct this system to work optimally.

In the absence of artificial light, people quickly adapt to a circadian rhythm where they are up to during daylight hours and asleep at night. As a result of the continual use of artificial light, night shifts at work, and travel across time zones, people’s circadian rhythms can become out of whack.

Cancer development may be influenced by circadian disturbance, as evidenced by an increasing body of research. Circadian signals are involved in cell growth and division, which has consequences for how mutations and DNA damage might be induced. The generation and metabolism of hormones, as well as the immune system, are all influenced by the body’s circadian rhythm.

Circadian rhythm has a broad impact on numerous biological systems, therefore its disruption has the potential to have multiple ties to the development of cancer, including breast cancer as well as cancers of the liver, colon, lung, pancreas, and ovaries.

Shift workers have an increased risk of cancer because their circadian rhythms are disrupted by nighttime labor, a practice known as “shift work.” There is enough data to conclude that shift employment is “probably carcinogenic,” according to the International Agency for Research on Cancer (IARC).

Circadian rhythm and exposure to carcinogens may interact, raising the idea that disrupted circadian timing may enhance the risk of other risk factors.

Obstructive Sleep Apnea

Obstructive sleep apnea has been the primary focus of research on the link between sleep disorders and cancer (OSA). A condition called hypoxia occurs when there are frequent pauses in breathing, causing fragmented sleep and a decrease in the amount of oxygen in the blood.

Sleep apnea and its associated hypoxia (lack of oxygen in the blood) have been shown in animal studies to promote tumor growth. A cancer-friendly environment may be created in people due to a variety of sleep apnea effects.

Chronic low-grade inflammation, oxidative stress, and fragmented sleep are all worsened by hypoxia because hypoxia is thought to impair the function of some immune cells, making them less efficient at fighting cancer cells. Hypoxia-induced sleep apnea may contribute to cancer risk since tumors include areas of low oxygen.

OSA has been linked to cancer in numerous research, however, the results have not been generally positive.

Researchers in both the United States and Spain have discovered an elevated risk of cancer death among those with moderate or severe OSA. OSA and breast cancer have been linked in smaller studies. Prostate, uterine, lung, thyroid, and kidney malignancies, as well as malignant melanoma, are all more common in people with severe OSA.

Researchers have observed varying patterns of cancer risk and mortality in people with OSA, and other studies have even found fewer cancer cases in those with OSA. This could be because different methods of evaluating OSA have been used, there is little data on which patients were treated for OSA, and there are possible linkages between OSA and other illnesses like heart disease, obesity, and diabetes that could alter cancer risk.

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Sleep and Cancer Progression

Cancer’s growth and progression may be influenced by the quality of one’s sleep. Research is needed to determine whether sleep affects hormones, metabolism, and inflammation, which may alter cancer’s aggressiveness, although this is a possible link.

Over-sleeping has been linked to an increased risk of death from breast cancer and other reasons in women with breast cancer, according to one study. Breast cancer recurrence was found to be faster in women whose sleep patterns were out of sync with their circadian rhythms.

A study on sleep and colorectal cancer found a link between shorter sleep duration and an increased risk of cancer death, but this study, like many others, simply found a link, not proof of a cause and effect.

Hypoxia and sleep fragmentation caused by obstructive sleep apnea may make tumors more likely to spread to other regions of the body and contribute to cancer progression.

Sleep and Cancer Treatment

If we learn more about the circadian rhythm, we may be able to develop more effective cancer treatments that take advantage of the patient’s sleep patterns.

Depending on the time of day the medication is administered, cancer cells may be more susceptible or resistant to the treatment. Circadian timing affects many of the proteins, enzymes, and receptors that cancer medicines aim to target on the cell surface.

Chronotherapy is a cancer treatment component that uses a person’s circadian rhythm to maximize radiation, chemotherapy, or immunotherapy. It is currently in development. Chronotherapy may be able to help cancer treatments kill more cancer cells while minimizing damage to healthy tissue, according to some researchers.

New cancer-fighting medications may also be created by utilizing our growing understanding of circadian rhythms. Several forms of cancer have demonstrated promising early-phase effects from medications that control the “on/off” signals for cell development that are part of the circadian rhythm.

Cancer patients’ recovery and response to therapy may be affected by their ability to get a good night’s sleep. When it comes to breast cancer surgery, poor sleep has been linked to higher levels of pain, longer hospital stays, and an increased risk of complications in women.

Obstructive sleep apnea may affect the efficacy of several cancer treatments, according to studies. Some types of chemotherapy and radiation therapy have the best effect when oxygen levels in the tumor tissue are high, therefore hypoxia from disturbed breathing may interfere with these therapies.

Frequently Asked Questions About Sleep and Cancer Risk

Does Sleeping With a Light on Increase Cancer Risk?

Some study suggests that exposure to artificial light at night may affect cancer risk, albeit it is not conclusive.

Nighttime darkness is a significant contributor to the body’s circadian rhythm because it causes the production of melatonin. Melatonin has been found in animal tests to prevent tumor growth and aid in the repair of DNA damage in cells. So, theoretically, sleeping with the lights on could disrupt the body’s normal circadian rhythms, so favoring the growth of cancer.

An increased risk of prostate cancer was found to be connected with sleeping in a brightly lit bedroom, whereas a lower risk of breast cancer was found to be found in an observational study of persons and their nighttime artificial light exposure. A lot more research is needed to understand whether or not light exposure during sleep increases the risk of cancer, given these conflicting results.

Can You Get Cancer by Sleeping Next to Your Phone?

Sleeping near your phone does not increase your cancer risk. Non-ionizing radiation, the sort of energy emitted by cell phones, does not cause DNA damage; instead, its sole known biological effect is warmth. Cell phone users have not been shown to have a higher risk of brain tumors or other types of cancer in studies conducted yet.

Despite the fact that there is no conclusive evidence linking cell phones to cancer, several experts advise against using your phone for extended periods of time while holding it close to your head. As a result, storing your phone in a nightstand or drawer may be the best option.

Technology in the bedroom can cause sleep disturbances, which may improve your sleep if you don’t bring your phone into the bedroom with you.

Does Sleeping With a Bra Cause Breast Cancer? 

There is no link between wearing a bra while sleeping and an increased risk of cancer. Studies have shown that wearing a bra while sleeping does not increase one’s chance of developing breast cancer in any way, and there is little to no convincing biological explanation as to how the DNA mutations in cells caused by wearing a bra while sleeping might lead to cancer.

Sleep and Cancer Caregivers

Caregivers of cancer patients face their own sleep issues in addition to those of the person they are caring for. An estimated 89% of caregivers for breast cancer patients said they had trouble sleeping in one study.

There are many factors that might contribute to carers’ sleep problems, including interruptions during the night to provide care, elevated stress and anxiety levels, and a lack of time for self-care. As a result, the lack of sleep might put their own health in danger, increase their depression, and make it difficult for them to deliver high-quality healthcare.

Caregivers must take care of themselves, which includes establishing a sleep routine that is as regular as possible. Some aspects of caring can be assisted by other family members, friends, or local groups, allowing the carer to dedicate more time to their own physical and emotional well-being.

Long stretches of shift work may increase cancer risk.

Cancers of the breast, colon, ovaries, and prostate may be more likely if the body’s “biological clock,” which regulates sleep and tens of thousands of other activities, is disrupted. Working overnight hours and being exposed to light for a long period of time might diminish melatonin levels, which can encourage cancer growth.

Take action: “It is vital to stay up with recommended cancer screenings, including mammograms, testing for colon cancer, and checking your prostate by your doctor,” Ruble notes.

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Cancer therapy’s side effects and emotions can disrupt sleep.

Anxiety, despair, exhaustion, digestive-system issues, breathing issues, hot flashes, night sweats, and pain can all keep you awake at night throughout cancer treatment.

Tell your doctor about your sleep deprivation. Ask if you can be interrupted less frequently while sleeping in the hospital. A combination of relaxation techniques and cognitive behavioral therapy can help. Ensure that you have a regular bedtime and wake-up time. Reduce your intake of caffeinated beverages and allow your circadian rhythm to be reset by spending time in the fresh air or sitting in a sunny window during the day.

Insomnia can bother cancer survivors for years and even decades.

“Lack of sleep has a big influence on anyone’s capacity to function in school or on the job,” Ruble adds. In young survivors, we’re discovering sleep issues, and we’d like to know if they play a role in their academic difficulties.”

What you can do: The long-term adverse effects of treatment may have a part in the sleep issues of survivors, but activities that disrupt sleep may also play a role, according to Ruble. A lack of exercise and staying up late to play video games or watch television can also get in the way, she explains.

Ways to manage sleep problems

If you’re having trouble falling asleep, make an appointment with your doctor so that you can obtain the treatment you require. You and your healthcare team can take efforts to help you get a good night’s sleep again.

  • Tell your doctor about problems that interfere with sleep. Pain or other side effects, such as urinary and bladder difficulties, or diarrhea, may improve your sleep if you receive therapy.
  • Cognitive-behavioral therapy (CBT) and relaxation therapy may help. It’s possible to relieve stress by engaging in these practices. Even a CBT therapist can help you learn how to replace negative sleep beliefs with positive ones, for example. Additionally, you may benefit from techniques like muscular relaxation, guided visualization, and self-hypnosis.
  • Set good bedtime habits. Keep your bedroom quiet and dark, and make sure your bed is comfy before you go to sleep. Do something else if you are having trouble winding down or falling asleep. A few hours before going to bed, stop using any electrical gadgets, such as a television or computer. Before going to bed, try not to overindulge in food or drink. While it’s crucial to be active throughout the day, exercising just before bedtime may make it more difficult to get a good night’s sleep.
  • Sleep medicine may be prescribed. If other methods fail, your doctor may prescribe sleep medication for a limited length of time. You’ll be prescribed a sleep aid based on your specific issue (such as difficulty getting asleep or difficulty remaining asleep) and any other medications you’re already taking.

Talking with your health care team about sleep problems

Make a list of questions to bring with you when you go in. Consider including the following concerns in your list:

  • Why can’t I fall asleep?
  • What issues should I bring up with you?
  • What can I do to get a better night’s sleep?
  • Do you have any suggestions for a sleep therapist who might be able to help me with my issues?
  • Is it possible that I should take a sleeping pill?
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