Poor sleep is associated with chronic disease and not getting enough sleep. I’ve always been a poor sleeper, but I’ve worked on improving it. I wear blue-light-blocking glasses after sundown in the evening. I either get 30 minutes of early morning light before 8 am or wear light therapy glasses in winter.
However, the single most critical factor for getting a good night’s sleep is getting early morning light as soon as you wake up. Morning light turns off melatonin, starts serotonin, and then ensures there is sufficient melatonin tonight.
In this post, I will examine the connection between lack of sleep and cancer risk. We’ll take a look at the microbiome connection with sleep as well. I’ll also look at the importance of sleep during cancer treatment, sharing some tips and tricks I’ve learned along the way.
Sleep and cancer risk
Sleeping problems are a risk factor for developing certain types of cancer. More chillingly, they may also affect the progression of cancer and the effectiveness of treatment. What is also known is that cancer can also affect sleep.
Symptoms of cancer and side effects of treatment may cause sleeping problems. A lack of sleep during treatment can foster the progression of the disease. This is why focusing on getting a good night’s sleep is critical to lower cancer risk and minimising progression through lack of sleep during treatment.
Although it’s impossible to eliminate cancer risk, getting a good night’s sleep may be a protective factor. For people with cancer, better sleep may improve their chance of survival.
Research has shown that different sleep components, including duration, quality, circadian rhythm, and sleep disorders, can affect cancer risk.
Duration
According to the Sleep Foundation, people who sleep less than six hours per night have a higher risk of death from any cause. One large-scale study also found that people with short sleep have an increased cancer risk.1
Short sleep duration is associated with a greater risk of colon polyps. Some research has tied reduced sleep duration to a higher likelihood of Non-Hodgkin Lymphoma and stomach, thyroid, bladder, head, and neck cancer. The link with bladder cancer resonates with me, as I have always had trouble with sleep.
Sleep duration is one of the easiest factors to influence by being disciplined with going to bed early. I’m now in bed by 9 pm every night. I might listen to a podcast, but I’m asleep before 10 pm. If I miss that window, I find it harder to sleep.
A review of analysis in the National Library of Medicine indicated that short sleep duration increased cancer risk in Asians and long sleep duration increased the risk of colorectal cancer.2
I suspect that the increased cancer risk from poor sleep is not so much quantity as quality.
Sleep quality
Sleep quality is an area that I continue to work on. Unfortunately, one of the unwanted side effects of having a neo bladder is the need to wake during the night to empty, leading to fragmented sleep. If I’d known this before the operation, I might have chosen the stoma for this specific reason.
One study in mice showed that fragmented sleep triggered inflammation that promoted tumour growth and progression. An observational study found a higher cancer risk in people who rated their sleep quality as intermediate or poor.
I don’t have any answers as t how to avoid fragmented sleep. Improvements seem to come from a combination of habits, including avoiding caffeine, a darkened room, an ambient temperature of 18c and supplementation with Valerian Root, Tart Cherry Juice or Melatonin if required.
Feedback from a sleep app like Sleep Cycle is also valuable for improving sleep quality.
Circadian rhythm
Another exciting area of research is the impact of artificial light on the circadian rhythm. Circadian rhythm is the body’s internal clock that spans a 24-hour day. Artificial light, screen time, night shifts, and travel can cause misaligned circadian rhythms.
Science shows that circadian disruption can play a role in cancer development. Specifically, circadian signals are involved in how cells grow and divide, with implications for mutations and DNA damage that can cause cancer. In addition, hormone production and immune function can be disturbed by a misaligned circadian rhythm.
Circadian disruption involves multiple links to the development of cancers, including breast cancer, liver, colon, lung, pancreas, and ovaries.
I have adopted several strategies to combat circadian rhythm disruption in this modern world. As I learned from a sleep psychologist, the number one strategy is to get at least 30 minutes of daylight after waking up. This simple measure resets the circadian rhythm and turns off melatonin, allowing it to replenish for the evening. It also switches on serotonin, the feel-good hormone.
During winter, when there is not enough daylight, I wear Re-Timer Light Therapy Glasses whose blue light mimics the effect of morning light. I also wear orange glasses an hour before bed in the evening and minimise screen time.
Sleep, hormones, and cancer
A Stanford University study shows how well you may help explain how mental well-being affects cancer recovery and progression.
Sleep problems seem to alter the balance of two hormones influencing cancer cells.
The first is cortisol, which helps regulate immune system activity, releasing cells that help the body fight cancer. Cortisol levels typically peak at dawn and decline throughout the day.
The study found that people who wake up repeatedly at night are likelier to have abnormal cortisol patterns.
Cortisol is triggered during times of anxiety and may play a role in the development and worsening of cancer and other conditions.
The other hormone affected by sleep is melatonin. Melatonin has antioxidant properties that prevent cell damage and can lead to cancer.3
Sleep and cancer progression
The impact of poor quality sleep on cancer progression is alarming. You may find that you are doing everything else to slow down or reverse cancer progression through treatment, diet, exercise, meditation and exercise. Still, if your sleep is poor, there is a real risk that cancer will continue to spread.
Research has shown that the impact of sleep on hormones, metabolism, and inflammation affects cancer’s aggressiveness.
A Nature journal study found that breast cancer’s metastatic spread accelerates during sleep. The study found that circadian rhythm hormones, including melatonin, directly promote tumour cell proliferation in a time-dependent manner. This finding provided a rationale for the time-based treatment of metastasis-prone cancers.4
A study published in Nature Journal found women who slept more than nine hours a night had a higher risk of death from breast cancer. Another study found a misaligned circadian rhythm to a faster breast cancer recurrence.
Alarmingly, a study on colorectal cancer showed that people with short sleep duration before their diagnosis had an increased risk of cancer mortality.
Obstructive sleep apnea also has a role in cancer progression. Hypoxia and sleep fragmentation enable tumours to metastasise more easily.
The sleep microbiome connection
As discussed elsewhere on this site, there is an inextricable link between the gut microbiome (GM) and cancer. Not surprisingly, there is also a link between the vitality and diversity of the gut microbiome and sleep. Good sleep equates to a healthy GM, and a healthy GM equates to good sleep. Of course, the converse is also true: poor sleep equates to the degradation of the GM, and a degraded GM leads to poor sleep.
One of the ways that GM influences health is through the well-established brain-gut-microbiome connection. Growing evidence suggests that the GM can also influence sleep quality. As we have seen, sleep quality rather than quantity may significantly affect the development and progression of cancer.
A recent National Library of Medicine study found that microbiome diversity correlated with increased sleep efficiency and total sleep time. It was also negatively associated with waking after sleep onset. The researchers found linkages between GM composition, sleep physiology, the immune system and cognition. They concluded that this might lead to mechanisms to improve sleep through manipulating the gut microbiome.5
It seems the GM also influences insomnia and circadian rhythm. Good sleep and mood are essential for health and keeping active. Research shows insomnia linked to biological rhythms, immune function, and nutrient metabolism. The GM regulates sleep and mental states through the microbiome-gut-brain axis.
Evidence indicates that microorganisms and circadian genes interact with each other. Another study published in the National Library of Medicine examined how the GM interacts with the circadian rhythms and emotions of the host. The GM is related to the host’s sleep and circadian rhythm. Stress can also affect the composition of gut microorganisms. It concluded that it is crucial to maintain the GM when treating mental disorders.6
Another study published in the Journal of Sleep Research looked specifically at the impact of treatment on the GM and the correlation with sleep disturbance. In the study, eighteen rectal cancer patients completed a sleep disturbance questionnaire and provided stool samples during chemo-radiotherapy. Analyses showed the impact of treatment on the GM was a significant factor associated with sleep disturbance.8
An article published in Science Magazine looked at the interplay between the GM and slept quality. The author noticed that while taking antibiotics, they experienced insomnia. The article found the link between sleep and the microbiome is circular. Poor sleep can create poor conditions for the GM, while poor digestive health can generate issues with sleep.
The pathway for the GM altering our sleep is via the vagus nerve. The vagus nerve plays a vital role in modulating mood, digesting food and regulating immune responses.
Suppose you disrupt the gut microbiota using an antibiotic or a high-fat diet. In that case, you see a disruption in the GM and corresponding circadian genes.
How to improve sleep through the GM
Thankfully, there are practical ways to improve our gut health and our sleep as a result.
Diet and exercise are the foundations for improving gut health. A diet high in fibre and fermented foods, as well as fruits and vegetables, can increase the microbiome’s diversity and reduce inflammation. There are options for over-the-counter probiotics, prebiotics and postbiotics, although they have drawbacks and benefits. Avoiding alcohol and fatty foods is a given.
Binge drinking disrupts the GM, something that I know about. A high-fat diet also has been shown to alter the GM in a way that isn’t beneficial and is inflammatory.
Sleep during treatment
Sleep also plays an integral role in cancer treatment effectiveness.
Cancer cells may be more vulnerable or resistant to treatments depending on when treatment is given based on your circadian rhythm. Cancer drugs target specific proteins, enzymes, and receptors on the surface of cells, all affected by the circadian rhythm.
There is ongoing research into optimising cancer treatments based on a patient’s circadian rhythm using chronotherapy. Thus, treatments can kill more cancer cells while reducing damage to healthy tissue.
Sleep also affects the way that patients recover and respond to treatment. Higher pain levels, extended hospital stays, and a greater chance of complications are related to poor sleep. This is ironic as, in my experience, hospitals are one of the worst places to get a good night’s sleep. There is constant artificial light, noise from machines and interruptions from periodic observations. In despair, patients often turn to sleep pills that do nothing to improve sleep quality.
Research about sleep apnea indicates that the condition may make specific cancer treatments less effective. Some types of chemotherapy and radiation therapy have the most significant effect when oxygen levels in the tumour tissue are high.
How cancer affects sleep quality
One of the difficulties in improving sleep quality while attempting to reverse cancer progress is that cancer and its treatment can disrupt sleep.
Conservative estimates show that half of all people with cancer have sleep problems. The rate of disrupted sleep is higher in patients with advanced cancer, reaching over 70%.
The causes of sleep disruption in cancer patients are multifaceted, including:
- Pain or discomfort from a tumour or treatment
- Gastrointestinal and urinary issues caused by cancer or its treatment
- Extended hospital stays
- Stress, anxiety, and depression from having cancer
- Infection and fever due to reduced immune function
- Cough or difficulty breathing
- Side effects from medications that interfere with sleep quality
- Disrupted sleep rhythm from napping
Cancer and cancer treatment may also result in sleep disorders, including restless legs and sleep apnea.
Tips and tricks to improve sleep
But all is not lost. There are some practical things we can do to improve our sleep. These methods enable me to sleep an average of 7 hours per night, falling asleep after 10 minutes with a sleep quality rating of over 80% as measured by the Sleep Cycle app. Not perfect, but the trends are improving. It’s a work in progress.
These are some of the things I have found to be effective.
- Daylight – Get 30 minutes of daylight upon waking or use light therapy glasses in the morning. This is the number one tip I received from a sleep psychologist. This is far more effective than cognitive behavioural therapy (CBT), although this may help in some cases.
- Sleep hygiene – Wear blue light-blocking glasses an hour before bed, especially in a hospital. Follow a consistent sleep schedule, have a bath an hour before sleep, and black out the bedroom. Maintain an ambient bedroom temperature of 18C. Minimise screen time in the lead-up to bedtime an hour before.
- Supplements – Experiment with supplements including Valerian Root, Reishi Mushroom and Tart Cherry Juice. Avoid sleeping tablets as they do nothing to improve sleep quality and have unwanted side effects. Eliminate, or limit the intake of caffeine, especially after midday.
- Sleep App – Get a sleep app like Sleep Cycle that will give you feedback on how different factors impact your sleep to measure what is and is not working. I’ve found a positive feedback loop from a sleep app helps reduce anxiety around sleep.
- Reduce stress through good diet, exercise and mediation and finding something meaningful to do.
- Look after your gut microbiome through exercise diet by eating more fibre fermented foods and taking resistant scratch as a supplement during cancer treatment and antibiotic use.
Another area that I’m experimenting with is intermittent fasting. It’s too early to say what effects this may have on sleep quality. I also know that a B12 deficiency from the neo bladder is also a factor in fragmented sleep that I keep an eye on.
If I find I can’t get to sleep with a racing mind, I take a teaspoon of honey or eat half of a banana which seems to do the trick.
Conclusion
As we have seen, there is a direct relationship between sleep and the development and progression of cancer. Sleep plays an integral role in the treatment of cancer as well. Underlying this relationship is the role of the gut microbiome in sleep duration and quality in a circular feedback loop. Practical strategies, including getting daylight as soon as you wake up, improving sleep hygiene and looking after the GM through diet and exercise, help ensure a good night’s rest.
References
- Cancer and Sleep; Available at URL: https://www.sleepfoundation.org/physical-health/cancer-and-sleep#:~:text=Sleep%20Duration,-Studies%20about%20the&text=Research%20has%20found%20that%20people,an%20increased%20cancer%20risk6
- Sleep duration and the risk of cancer: a systematic review and meta-analysis including dose–response relationship; Available at URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6249821/
- How Sleep Affects Cancer – Poor Sleep Alters Hormones That Influence Cancer Cells; Available at URL: https://www.webmd.com/cancer/news/20031001/how-sleep-affects-cancer
- The metastatic spread of breast cancer accelerates during sleep; Available at URL: https://www.nature.com/articles/s41586-022-04875-y
- Gut microbiome diversity is associated with sleep physiology in humans; Available at URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6779243/
- The Role of Microbiome in Insomnia, Circadian Disturbance and Depression; Available at URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6290721/
- Gut microbiota perturbation is associated with acute sleep disturbance among rectal cancer patients; Available at URL: https://onlinelibrary.wiley.com/doi/abs/10.1111/jsr.12915
- The Microbiome Impacts Sleep Quality, and Vice Versa; Available at URL: https://www.discovermagazine.com/health/the-microbiome-impacts-sleep-quality-and-vice-versa
- Sleep and Cancer; Available at URL: https://www.cancercouncil.com.au/podcasts/episode-12-sleep-cancer/
- Sleep Problems in People with Cancer; Available at URL: https://www.cancer.gov/about-cancer/treatment/side-effects/sleep-problems
- Improving night-time Sleep Problems; Available at URL: https://www.petermac.org/services/cancer-information-resources/can-sleep
