The Link Between Sleep & Breast Cancer

ISD Health Solutions ISDHS ISD Pink October Breast Cancer Awareness

October is breast cancer awareness month (Pink October), and ISD Health Solutions wanted to explore the long-term sleep deprivation may increase the risk of some malignancies. But sleep, and cancer is linked in other ways as well. Getting a good night’s sleep following cancer treatment is tough and might be a lifetime issue for survivors. As a result, persistent sleep length, timing, or structure disruptions can cause broad difficulties in various physiological systems, including those that govern energy balance, immunological function, and cognitive ability, among others. Many, if not all, of these systems, are changed during cancer genesis, development, metastatic spread, therapy, and recurrence.

A recent study has shown that sleep alterations impact the development of chronic illnesses such as cancer in human and animal models. A typical observation is that prolonged disturbance of sleep and waking states before illness start is connected with an increased risk of cancer development in various malignancies, such as breast cancer. Furthermore, sleep disturbance following a cancer diagnosis is frequently connected with worse results. Recently, evidence has gathered that cancer can disrupt neural networks that govern sleep and wakefulness. During and even years after treatment, cancer patients frequently have trouble falling asleep, difficulty remaining asleep, and significant exhaustion.

Cancer, in addition to its psychological stress, may impair sleep homeostasis through changes in host physiology and currently unknown processes. Furthermore, cancer therapies (e.g., chemotherapy, radiation, hormonal, and surgical) may exacerbate sleep difficulties through complicated biological processes that are still unknown. This creates a “chicken or the egg” situation in which it is unclear whether sleep disturbance causes cancer or whether cancer disturbs sleep. According to recent research published in the journal Cancer Causes and Control, women who have even brief interruptions in their sleep have a greater risk of developing breast cancer than those who sleep undisturbed. This is significant because poor quality sleep and a lack of sleep can alter the body’s natural hormonal functioning. That’s because the hypothalamus, part of the brain involved in hormone production, also regulates the sleep-wake cycle.

Are you sleeping well? If not, you may be at an increased risk for breast cancer. In fact, women who experience even brief periods of sleep disruption have a higher incidence of breast cancer than those who sleep uninterrupted.

What is it about insomnia and interrupted sleep that increases the risk? The answer has a lot to do with how your body handles hormones. Research shows that estrogen plays a significant role in breast cancer development, so anything that impacts estrogen levels can potentially impact your risk. The link between sleep disruptions and hormonal changes is not as well understood, but there are theories. It’s known that during REM (rapid eye movement) sleep, we experience higher levels of growth hormone, which can stimulate tumour growth; some experts believe this is why people who don’t get enough sleep have an increased risk of developing certain cancers. Also, abnormal melatonin levels can affect the timing of when a woman ovulates—which means she might be more likely to get pregnant before her eggs are fully mature (and therefore at greater risk for miscarrying). The hypothalamus, part of the brain that regulates hormone production, also plays a role in sleep regulation. Research shows that poor quality sleep and lack of sleep can disrupt normal hormonal functions in your body. That’s because the hypothalamus, which produces hormones like testosterone and estrogen, also regulates the sleep-wake cycle.

It can disrupt this process when you have trouble sleeping at night due to stress or other factors (like an old mattress). This disruption can lead to changes in levels of certain hormones—namely estrogen—that play a role in breast cancer risk. Your body produces two types of estrogen: estradiol and estrone. Estradiol promotes cell growth, while estrone promotes cell death. Estradiol is the primary type of estrogen produced before menopause, but following menopause, there’s more estrone than estradiol in the body. Elevated levels of these hormones can lead to breast cell growth (which increases your risk of developing breast cancer). Sleep’s role here is still unclear because some studies show that women who report getting less sleep have higher levels of both types of estrogen in their blood. Still, other studies don’t find this connection or find it only among subgroups like obese women or premenopausal women with a family history of breast cancer.

Cancer can create major sleep disruptions, affecting the ability to fall asleep and stay asleep through the night. The National Cancer Institute reports that cancer survivors are twice as likely to have insomnia symptoms as people without a history of cancer. Insomnia can also lead to fatigue, another risk factor for breast cancer. A study published in the journal Cancer Epidemiology, Biomarkers & Prevention found that women with high levels of fatigue were more likely to experience hot flashes and night sweats than those with low levels of fatigue. As a result, fatigue may be associated with an increased risk for breast cancer in women with a history of the disease. The study also found that women with high levels of fatigue were more likely to experience insomnia, a known risk factor for breast cancer. Another study published in the journal Cancer Epidemiology, Biomarkers & Prevention found that women with high levels of fatigue had a 28 per cent increased risk of developing invasive breast cancer over a 14-year follow-up period. In addition to the effects of cancer treatment, a breast cancer diagnosis can lead to insomnia. Treating symptoms like pain or anxiety can help people fall asleep, but these issues often take time to resolve. A study published in the journal Cancer Epidemiology Biomarkers & Prevention found that women who developed breast cancer in their 40s were more likely than younger women with breast cancer—or those without breast cancer—to have sleep problems at least one year after diagnosis.

  • A growing body of research links sleeps disruption and circadian misalignment to subsequent tumour initiation and growth (Hansen, 2001; Schernhammer et al., 2006; Van Dycke et al., 2015). Given that the overall prevalence of sleep disorders is rising (Ferrie et al., 2011; Chattu et al., 2019), it is necessary to assess its contribution to tumorigenesis.
  • Notably, a prospective study of approximately 24,000 women by Kakizaki et al. (2008) demonstrated an inverse association between sleep duration and risk of breast cancer, where shorter sleep duration (i.e., six hours or less) was associated with an increased risk of breast cancer.
  • The association between sleep duration and the risk of breast cancer was further evaluated in a meta-analysis by Van Dycke et al. (2015). This systematic review showed that shorter sleep duration was associated with a higher risk of breast cancer, specifically among women with the lowest levels of socioeconomic status. Risk of Breast Cancer According to Menopausal Status.
  • Women currently in the perimenopause or postmenopause stages of the reproductive life cycle have an increased risk for breast cancer. A prospective study by Brinton et al. (1999) showed that women who experienced menopause at a younger age had a higher risk of developing breast cancer later in life than those who experienced menopause at older ages. In addition, a study by Cauley et al. (1999) found that women who experienced menopause at earlier ages were more likely to develop breast cancer than those who experienced menopause later in life. These findings suggest that the onset of menopause may be one factor associated with the development of breast cancer.

Research has shown that emotional support from family and friends can make a big difference in the quality of life of someone with cancer. People are often afraid of saying the wrong thing to someone with cancer. If you are open and honest and show your concern, then you can be a great support. Here are some tips that might help you.

So, what does all this mean? It means that if you’re not getting enough sleep, it could be setting the stage for breast cancer. A disrupted sleep schedule can disrupt normal hormone levels, increasing breast cancer risk by promoting cell growth. To reduce your risk of developing this condition, keep a consistent sleep schedule and avoid medications like Ambien or other sleep aids that can interfere with restorative sleep patterns.