Sleep and cancer

Key points

People with cancer report high levels of sleep problems and we know that poor sleep may be a risk factor for developing cancer.¹ In this article we look at what links cancer with sleep. We’ll cover:

• why sleep problems are so common with a diagnosis of cancer
• the benefits of good sleep for your overall health
• the relationship between poor sleep and cancer
• how cancer treatments can impact your sleep
• ways to improve your sleep after cancer.

Introduction

The incidence of insomnia for people with cancer is thought to be around double that of the general population but sleep disorders remain under-treated in this group.

We’re going to look at the many reasons why experiencing cancer can affect sleep and consider some steps to protect or improve sleep for people with cancer.We’ll look at sleep’s protective effects on our health and what’s known about how sleep can influence cancer risk.

We’ll explain how a cancer diagnosis and cancer treatments can affect your sleep plus what steps you can take during and following treatment to ensure you’re getting the best sleep possible.

Let’s start with a quick overview of what links your sleep to your health and wellbeing.

Sleep plays a vital role in maintaining your health

When we think of how to take care of our overall health, we probably consider healthy eating, regular exercise and taking care of our mental health. But there are four, not three, areas that we need to consider and the one we most take for granted is: sleep.

Prioritising our sleep is something so many of us just don’t do but it’s well established that good sleep’s essential for good overall health. Let’s find out why.

During sleep, your body repairs and regulates your cells, tissues and muscles. At the same time your brain processes thoughts, feelings and emotions that you’ve experienced during the day.

Sleep boosts our immune system, helps regulate our mood, gives us the motivation to exercise, eat well and go about our daily lives. So without good sleep, our bodies and minds can’t and won’t function at their best.

But when we talk about ‘good’ sleep what do we mean? For our sleep to be good, it needs to be of a suitable duration AND made up of quality sleep. Getting 12 hours of poor sleep will not have the same beneficial effects as eight hours of good quality sleep.

How do you know if you’re sleeping well? It’s quite simple: if you’re waking up feeling well-rested and restored, with energy to get through the day, then your sleep quality is probably good.

We know that poor sleep is linked to the development of disorders such as diabetes, cardiovascular disease and obesity. So it’s not a huge step to assume that our sleep can also influence our risk of developing cancer.

Can sleep influence the risk of developing cancer?

This is a field of research that’s growing rapidly. Studies have looked at whether how long we sleep (long or short duration) or how well we sleep (sleep quality) can influence our risk of going on to develop cancer.

To investigate the links between sleep and cancer risk, researchers often compare how long people sleep (i.e. sleep duration) with whether they then go on to develop cancer or not.

Most of these studies have looked at whether sleep duration, either short or long, could be associated with risk of cancer.^{1 2 3 4 5} The results definitely aren’t clear cut.

Many studies suggest that short sleep duration increases the risk of cancer whereas some find associations between certain cancers and long sleep duration. Other studies find no definite link at all between how long we sleep for and our risk of cancer.

Recently, researchers examined data from nearly 24,000 people recruited to a health research study.¹ They looked at data collected from participants across nearly eight years and compared their average sleep time at the start of the study with whether they went on to develop cancer and other diseases.

Results showed that compared to average sleep (7-8hrs), short sleep (less than 6hrs per day) was associated with more than a 40% increased risk of overall cancer.

In contrast, a meta-analysis (where the results of many studies are compared together) looked at the results from 65 studies and showed no increase in risk of cancer overall.²

There are studies that show associations between specific types of cancer and sleep duration, such as breast cancer³ and colorectal cancer.² But when we talk about ‘association’ it means that people with the specific cancer had shorter sleep times than people who didn’t have that cancer.

It doesn’t mean that the short sleep time was the reason for developing the cancer. It could be a factor in the development of cancer and, most likely, it’s just one part of a more complex picture.

Insufficient sleep has been linked to risk of cancer when looking at individual populations, geography or ethnic backgrounds.

For example, in the meta-analysis discussed above,² studies were grouped by the geographical locations of Europe, USA and Asia and a link was found between short sleep duration and cancer risk in the Asian population only.

In another study, the cohort was made up of uniquely Mexican-American participants and the results showed an increased risk of cancer in participants who slept less than six hours per night.⁴

The potential reasons for certain populations having higher risk are not clear but they could be due to differences in culture, lifestyle, genetics or a mix of all three.

While it’s not possible to generalise and say that sleep duration influences cancer risk, we do know that insufficient sleep has a negative effect on overall health so ensuring you’re sleeping well can only be a positive thing for your wellbeing.

If you feel like your sleep isn’t optimal, or that you’re struggling with a sleep problem, it’s a good idea for your general health and wellbeing to try to address this. An excellent first step is to take our short sleep quiz to see how we can help you to improve your sleep.

The biology of sleep and cancer

When we talk of ‘cancer’, it’s important to understand that it’s not one distinct illness. According to Cancer Research UK, there are actually more than 200 different types of cancer.

Cancer is an umbrella term for a huge number of different malignancies that all affect the human body in their own way.

The defining feature that brings all cancers together is that they all cause the uncontrolled growth of cells within the body. So given that the word cancer is used to define a large and diverse group of illnesses, the relationship between sleep and cancers is also going to be complex.

Looking at the research data, it appears that certain cancers may be more influenced by sleep than others. It’s also reasonable to assume that even when two people have the same cancer type, one person’s sleep may be disrupted more than another.

Regardless of the type of cancer studied, when looking at the biological links between sleep and cancer, research mainly focuses on three areas:

• disruption of circadian rhythms
• immune function
• melatonin secretion.

So we’ll explore each of these three areas in a little more detail.

Cancer, clocks and circadian rhythms

Many studies have found links between the body clock, circadian rhythms and development of cancer. But what exactly does all of this mean?

Our body runs on a roughly 24hr schedule which we call our circadian rhythm. This schedule is naturally synchronised to sunset and sunrise and is controlled by the body clock, which is the name given to specialised cells that make up a part of the brain called the suprachiasmatic nucleus (SCN).

The human body actually has many different clocks which are responsible for timing regular events in the body. All of these minor clocks are under the control of the master clock in the brain.

They control when certain chemicals in the body rise and fall, regulating a host of bodily functions to ensure that your body works as it should. Think of the master clock as the head office and all the smaller clocks are departments within the company (the body).

The master clock responds to light and dark signals to keep all the smaller clocks in line. So, when we open the curtains in the morning and the sun floods in, light passes into our eye, signals are relayed to the SCN and this leads to all of our clocks being synchronised.

This is like head office sending out memos to say, ‘It’s daytime-let’s get to work!’ and each department then synchronises its clock and starts its tasks. Jobs might include controlling our temperature, starting processes that we use during our waking hours or stopping production of molecules that were needed overnight but not during the day.

These rhythms are what keep the balance in our bodies and allow us to remain healthy and go about our daily lives with energy. Unfortunately, there are many things that can disrupt that balance.

A simple example of this is jetlag. Flying across time zones can throw your body’s circadian rhythms out of sync and the result is that you can feel headachy, sick or just not quite right.

A similar effect can occur when you don’t get enough sleep or even when you oversleep and wake up feeling groggy. These are short-term disruptions to your circadian rhythm and they can be corrected by getting enough sleep, at the right time of day.

Problems occur when these short-term disturbances become regular. If you’re constantly at odds with your natural rhythms then the body is left trying to maintain balance amidst chaos.

Imagine head office sending out its morning memo at 3am. Or sending out multiple copies of the morning memos throughout the day. Or at different times every day. All the departments will end up confused and disorganised and the whole system crumbles.

This is what we mean when we talk about circadian rhythm being disrupted.

It’s well known that disruption of our circadian rhythms is a risk factor for many different forms of cancer.⁶

In our modern, fast-paced world, we often keep to schedules that go against our natural circadian rhythms. According to one study, 75% of the working population in industrialised countries work atypical hours (defined as outside of 8am-5pm core hours).⁷

So many of us stay up late, work irregular shifts patterns and rise at hours when we should normally be sleeping. By going against our natural circadian rhythms, we could unknowingly be influencing our cancer risk.

Many studies have shown that long-term shift work can come with a higher risk of cancers such as those involving the breast, colon, ovaries and prostate. However, when it comes to breast cancer and shift work, several large studies from 2021 have failed to find a link between shift work and cancer,^8 9 so this association is definitely not clear cut.

Nonetheless, minimising disruption to our normal bodily rhythms is something we should all try to take on board, especially so if you’re a shift-worker or work irregular hours.

We’ve got lots of tips to help shift-workers to sleep well and general recommendations are that people who work shifts shouldn’t overlook the importance of regular cancer screening programmes.

Keeping up with mammograms, having a prostate check or making sure you carry out the recommended screening for colorectal cancer can all help to identify cancers early. And this advice isn’t limited to people who work shifts ― earlier diagnosis can improve success rates for treatment of cancer.

Can we use circadian rhythms to improve cancer treatment outcomes?

So we’ve looked at how disruption to our natural rhythms through poor sleep, irregular sleeping patterns and our work schedules may influence cancer but there’s also a more positive angle between cancer and circadian rhythms.

Research has shown that people with cancer who keep to regular sleep/wake schedules have better outcomes and quality of life than people with irregular schedules and poor sleep.¹⁰

What this means is that by keeping to a relatively consistent daily routine of going to bed at a reasonable time, prioritising sleep and avoiding things that disrupt our circadian rhythms, we’re probably bolstering our defences against cancer.

Cancer chronotherapy ^11 12 is the name given to describe therapies that use the timing of when cancer drugs are given, in line with the person’s circadian rhythms, with the aim of reducing drug side-effects and actually improve prognosis.

Melatonin

Another area that’s received a lot of interest from the cancer research community is exploring the links between melatonin and cancer. Melatonin is a hormone which is key to making us feel sleepy.

Throughout the day, levels of melatonin remain very low in the body. As the day wears on and darkness falls, melatonin production increases and the end result is that you feel sleepy.

The morning sunlight streaming in through our eyes signals the end of production of melatonin, which is key to making us feel sleepy. In the morning, we wind down production of melatonin and so don’t feel sleepy.

When we extend our days with artificial light — perhaps spending our evenings glued to social media or engrossed in a series on the TV — we’re unwittingly bathing ourselves in light sources that can confuse our melatonin production.

But how is melatonin linked to cancer? Scientific research has shown that melatonin actually has many anticancer properties. It’s been shown to have anticancer effects against skin cancer, ovarian cancer, blood cancers, lung cancers…^13 14 15 the list is ever-growing.

On the flip-side, people who have reduced melatonin levels are actually at higher risk of developing cancer.¹ Melatonin levels can be supressed by insufficient or fragmented sleep,  exposure to artificial lighting and anything else that can disrupt the circadian rhythm.

One good thing to come from our better understanding of melatonin’s cancer-protective properties is that it’s now being investigated to see if it can be used alongside conventional cancer treatments to improve their effectiveness.

This doesn’t mean we should all be rushing to take melatonin. For a start, it’s only available as a prescription drug in many parts of the world (the UK and European Union, Japan, Australia and Canada) and it’s a hormone that plays a part in many functions in the body, so melatonin is not something to be taken without medical supervision.

The healthy way to keep your melatonin levels at their best is to get adequate exposure to sunlight during the day. If you’re resting or can’t go outside during your treatment, it’s sensible to reduce your exposure to bright lights and screens in the evening.

Making sure that your bedroom is as dark as possible can also help to signal to your brain to produce melatonin, so dark blinds or even black-out curtains can be helpful.

Immune function

Our body clock controls when we sleep and wake and it also plays a critical role in optimising immune function.¹⁶ While we sleep our immune system ramps up its activity and the body actually experiences higher levels of inflammation than during the day.

The body clock regulates when the levels of certain molecules of the immune system rise and fall. During our sleep, when our body’s busy repairing muscles and carrying out housekeeping tasks to remove toxins and waste, levels of immune molecules naturally rise during the night to carry out their roles in these tasks.

Recent studies show links between activity and sleep patterns in opposition to the natural body clock (including night-shift work) and raised levels of inflammation in the body.

Delayed sleep patterns can disrupt the normal body clock. If you frequently stay up late (for work or pleasure) and sleep through the day this disruption to your body clock leads to chronic inflammation in the body.

During the night, as repairs and maintenance are complete, the body clock signals for inflammation levels to decrease and your body gets ready to start another day.

If you’re someone who stays up very late or works a night-shift then your body clock naturally wants to carry out these tasks during the night, when you’re awake.

So the body clock sends signals to increase inflammation while you’re working, socialising or bingeing Netflix — signals that work best when the person is asleep.

When you go to sleep at a time that doesn’t align with your natural body rhythm this further confuses the body clock because sleep is the time for repair. Inflammatory molecules that were already raised during the night stay high in the body while you’re sleeping.

The net result for those who experience frequently poor sleep or engage in night-shift work is constantly raised levels of inflammation compared to people who sleep at times that align with their natural body clock.

Sleep disturbance is one of the most commonly reported complaints in people with cancer

Many studies have highlighted that people with cancer commonly struggle with their sleep.^17 18 For some people the sleep disturbance may predate their diagnosis but for others it may be a symptom of the cancer or result from learning that they have cancer.

Many people with cancer encounter sleep problems during and after treatment. So it’s clear that at every stage of a cancer journey, sleep can be compromised. We’ll have a look at each step and what could be affecting sleep.

Symptoms of cancer can disrupt sleep

For some people, sleep problems can occur before they’ve even received a diagnosis but can be an indirect effect of their cancer. A growing tumour can lead to all sorts of symptoms that can interfere with night-time sleep, such as:

• digestive issues: nausea, vomiting, diarrhoea or constipation
• pain
• breathing difficulties
• fever
• itching
• bladder issues
• excessive daytime tiredness leading to naps
• non-specific feelings of discomfort from the tumour.

In addition, the very process of a tumour growing can cause changes in the body which lead to sleep problems without you being able to specifically pinpoint a reason behind the lack of sleep.

So, as you can see, the stage is often set for developing sleep problems even before a person is aware of their cancer.

Diagnosis

A cancer diagnosis is lifechanging and can be devastating. It’s no surprise that getting this news will affect how you feel and can affect your sleep. Many people with cancer will experience stress, anxiety or depression as a result of their diagnosis.

We know that there’s a strong relationship between sleep and mental health and that good sleep can have a positive effect on your mental wellbeing. So if you’re feeling overwhelmed by depression, anxiety or stress then taking steps to optimise your sleep could help to reduce these feelings.

You may find it helpful to set yourself a consistent wind-down routine at this point. Keeping to a similar routine can help you to sleep and provides you with some level of control during a time of considerable uncertainty.

It’s perfectly normal to feel a whole host of different emotions after diagnosis and these can easily intrude into your sleep at night. Some people may have trouble falling asleep while others may wake in the night and struggle to fall back asleep as they process their diagnosis.

If you’re struggling to fall asleep, stay asleep or get back to sleep during the night then it might be useful to try implementing some thought-blocking techniques to help you to clear your mind and get to sleep.

It’s important that you don’t just ignore sleep problems or consider them insignificant in comparison to a cancer diagnosis. Addressing sleep problems when they arise is the best way to combat them and setting up good sleep habits as early as possible after diagnosis can only be beneficial.

If you’re struggling to sleep and it’s interfering with your daily life and how you feel, get in touch with us or speak to your healthcare provider. Sleepstation’s programme is entirely medication-free and can provide you with the tools you need to take back control of your sleep.

Cancer treatments can affect sleep

No two cancers are the same and everyone’s body will respond to cancer in its own way. This is at the crux of why there is no single ‘cure’ for cancer. In effect, each cancer is unique and will respond differently to treatment.

As such, treatments for cancer vary both by individual and depending on the cancer type. However, a common feature of all cancer treatments is that they have the potential to disturb your sleep.

Generally, cancer treatment will involve one or more of the following approaches:

• surgery
• chemotherapy
• immunotherapy
• radiation therapy
• hormone therapy.

After many of these treatments it’s common to require a period of rest and recuperation, which can include taking naps, going to bed earlier or sleeping for longer. While these measures are absolutely crucial for the recovery process, it’s worth keeping in mind that once you feel better, you should try to go back to a regular sleeping routine.

Continuing to sleep at irregular times, nap during the day or sleep for extended periods during the night can all encourage poor sleep habits to develop and can contribute to developing insomnia.¹⁹

We’ll go over each type of treatment and how it might affect your sleep in a little more detail.

Surgery

Prior to any surgery, it’s natural to feel some anxiety and worry and this may interfere with sleep in the run up to the surgery date.

A study from Brazil has shown that one way to reduce anxiety before cancer surgery is through being well-informed about the procedure.²⁰

When participants were given detailed information about their surgery beforehand, their resulting anxiety levels were much lower than those who didn’t know what to expect about their surgery.

This suggests that if you’re preparing for cancer surgery, it’s probably helpful to ensure you have all the information to feel well-informed about the procedure. By knowing what to expect, anxiety levels may be easier to manage and, as we know that anxiety and sleep affect each other, this may help you to sleep better in the run-up.

Following surgery for cancer, you may experience sleep disturbance during your recovery. Your body will be working hard to recover and repair itself after surgery and this can impact on your sleep. You may feel discomfort or pain that interferes with your sleep or anxiety about how the surgery has gone.

It’s been shown that sleep can influence surgical outcomes.²¹ People who report poor sleep before surgery risk worse outcomes in terms of recovery time and levels of pain, nausea and vomiting experienced post-surgery.

Conversely, ensuring your sleep is as good as it can be during this period is essential for good recovery. Good sleep post-surgery can aid wound healing, reduce inflammation and speed up recovery time.

Before surgery, it could be helpful to assess your bedroom set-up and ensure it’s primed for a restful recovery when you get home. If you’re going to be recovering in hospital, it’s worth considering how your hospital time may affect your sleep too.

Hospitals are generally bright, busy and noisy. You might benefit from ear plugs to help you sleep well in hospital or you might choose an eye mask to block out the light. Even taking your favourite pillow, blanket or night-time reading may be worth considering for your time away from home.

Chemotherapy, immunotherapy and radiation therapy

With these therapies, the aim of treatment is to kill the invasive cancer cells. This results in your body putting in considerable effort to rid itself of all the resulting dead cells and this huge endeavour can have a big effect on your sleep.

In addition, side effects from these treatments can include complaints such as headaches, nausea and digestive upset and pain. All of these have the potential to disrupt your sleep. Thankfully, there are a variety of medications you can take to limit symptoms during and following these treatments.

While you can’t predict or control how your body will respond to these therapies, you can take control of your sleep during this time. There’s a host of simple sleep techniques you can apply yourself to try to optimise your sleep as you go through treatment.

Even seemingly small things like adopting good sleep hygiene, setting up a good wind-down routine and limiting screen time in the evenings can help to improve your sleep during treatment.

Hormonal treatments

Several cancers are also treated by medication that targets certain hormone pathways. When we alter the normal hormonal pathways in the body, this can have a huge effect on our sleep.

Hormone therapies are commonly used in the treatment of breast and prostate cancers and people often report night sweats to be one of the symptoms that disrupts their sleep during these treatments.¹⁷

If your treatment involves hormone therapies, it may help to keep your bedroom slightly cooler during the night and opting for cotton or linen sheets and nightclothes can help to wick away moisture from the body.

Steroids, anti-sickness and other medications

During your treatment, you may receive additional medication alongside your primary treatment, such as pain medication, steroids, antibiotics or medication to reduce nausea. Many of these drugs can interfere with sleep.

Regardless of the treatment protocol, your treatment team will be aware that certain drugs or combinations may interfere with sleep, so they’re often given at specific times in the day to minimise the effects they should have on sleep.

It’s really important that you let your healthcare provider know if your sleep is being affected by your treatment. Good sleep is crucial to good recovery and there’ll often be options available to enable you to improve your sleep, so don’t suffer in silence.

Post-treatment

Once treatment has finished, the recovery process within the body continues for some time. Recovery from cancer doesn’t have a defined timeline and the amount of time it takes to recover physically and emotionally will be highly individual.

Even after finishing treatment, going into remission and being given the all-clear, many cancer survivors struggle emotionally with worries about recurrence, progression or survivor guilt.

Levels of depression, stress and anxiety are reported to be higher in cancer survivors and we know that our mental health and sleep can have big effects on each other.

It’s a sad fact that many people who have gone through cancer treatment report problems sleeping and we know that rates of insomnia are high in cancer survivors.

As we’ve talked about earlier, insomnia can be a symptom of cancer even before diagnosis and it can also develop following diagnosis and during treatment. It’s not surprising that many cancer survivors report insomnia once their treatment is over.

Cancer-related insomnia can persist for years after treatment ends²² and cancer survivors report much higher levels of sleep problems than the rest of the general public.²³

Even with plenty of evidence to show that people who experience cancer have much higher rates of insomnia and sleep disturbance, within cancer care settings sleep disorders remain an overlooked problem.

A lack of available services often leads cancer survivors to try to live with their sleep problems or to look for ways to self-manage their symptoms. Many cancer survivors turn to sleeping tablets as a way to treat their sleep issues, even though medication is not a good long-term solution.

Thankfully, there are treatment options available that are highly effective. Nobody should feel like they have to live with insomnia and many people don’t realise that this sleep disorder is highly treatable. So if you’re experiencing a sleep problem, speak to your GP about it or contact us here at Sleepstation.

Cognitive Behavioural Therapy for insomnia is highly effective during and following treatment for cancer

Insomnia can affect people at all stages of their cancer journey and can continue to be a problem for cancer survivors. The gold standard treatment for insomnia is cognitive behavioural therapy for insomnia (CBTi) and it’s also been shown to be the most effective treatment for insomnia in the context of cancer.²⁴

CBTi is a form of therapy which aims to improve sleep habits and behaviours by identifying and challenging thoughts and behaviours that affect a person’s ability to sleep or sleep well.

It can help to get the person’s circadian rhythm back in time with the natural day/night cycle if they’ve got used to daytime naps or sleeping at irregular hours — problems often associated with people being treated for or recovering from cancer.

CBTi is well-suited for use by people with cancer or following cancer treatment as it’s completely drug-free. There’s therefore no potential for it to interfere with cancer treatment protocols.

Unlike sleeping pills, the effects of CBTi won’t just wear off when you finish the course. The results are long-lasting and it provides you with the tools necessary to take control of your sleep and work through any subsequent reoccurrence of symptoms.

Numerous clinical trials and studies have shown that CBTi is a valuable tool for people undergoing treatment for cancer and for helping cancer survivors who are experiencing insomnia.^{19 25 26 27}

Results have shown that CBTi can significantly improve sleep in people with cancer, helping to reduce the time it takes to fall asleep, reduce night-time awakenings and increase the amount of time people spend asleep in bed each night.²⁵

CBTi doesn’t just improve sleep. We know that when we sleep well, our mental health gets a boost and data has shown that people with cancer can also see improvements in their quality of life and mood after CBTi.²⁵

CBTi is what we use at Sleepstation and we know first-hand just how effective this technique can be. Our programme is drug-free, fully supported by sleep coaches and shown to be effective in improving your sleep after just three sessions.

No matter where you are in your cancer journey, there are options available to help you improve your sleep.

So please don’t ignore poor sleep or think that it’s something you have to put up with when you have cancer. You can see how we can help you by taking our quick and easy sleep questionnaire.

Whether it’s by reassessing your sleep habits, helping you to adopt better sleep hygiene or commencing a course of CBTi to conquer your insomnia, Sleepstation can provide the help and support you need to get your sleep back on track.

Summary

• Sleep problems are extremely common in people with cancer.
• Poor sleep may be a risk factor in the development of cancer.
• Taking steps to improve your sleep can benefit your overall health and wellbeing.
• No matter where you are in your cancer journey, there are always options available to help you improve your sleep.