MENUCancer and Sleep
Understanding sleep cycles, circadian rhythms and how cancer and treatment can affect sleep
Human beings cycle in and out of the four sleep stages throughout the night. Ideally, you’ll have dream stages every 90 minutes and wake up rested and ready to go in the morning. However, every person has a master body clock that can get out of sync with the external world. Add a cancer diagnosis to the mix and while sleep becomes even more essential to good health, it can also be harder to come by based on your personal situation.
We sat down with Deidre A. Conroy, Ph.D., the clinical director of the Behavioral Sleep Medicine Program at Michigan Medicine, to understand how cancer and the treatment of cancer can affect a person's sleep and what promising therapies exist to treat sleep problems.
Q. Can you explain how the human sleep cycle works in general?
Sleep is regulated by very sophisticated systems in the brain. In one system, our exposure to light or darkness sends a signal to the suprachiasmatic nuclei, also known as the master clock of the brain, to regulate our body’s rhythms, also known as circadian rhythm. Another system in our body, called the homeostatic system, keeps tabs on how long we have been awake. Basically, the longer you stay awake, the sleepier you become.
Sleep-wake cycles are controlled by this 24-hour master clock. The master clock regulates all kinds of bodily functions, such as performance, alertness and mood. It also regulates production of melatonin, a natural hormone in the body that helps to regulate sleep. When it is dark, your body produces more melatonin, promoting sleep. When it is light, you produce less.
However, sometimes our internal circadian rhythm gets out of sync with the outside world. When this happens, sleep disturbances can occur.
Q. How does a cancer diagnosis fit into this process?
There are many ways a cancer diagnosis and subsequent treatment can affect a person’s sleep. First, a person could be predisposed to a sleep problem like insomnia, even before cancer. If a person has anxiety, for example, a cancer diagnosis might be the event that precipitates, or causes, a bout of insomnia.
Insomnia in cancer is common, with 30 percent to 60 percent of patients reporting difficulty falling asleep or staying asleep. Being worried about falling or staying asleep can perpetuate the cycle. We know sleep disturbances, with or without cancer, are connected to a number of negative health consequences, such as fatigue, depression and increased pain.
Q. How does cancer treatment affect a person's sleep?
It largely depends on the individual and his or her treatment plan. For example, one study reported that chemotherapy disrupted circadian rhythms in women with breast cancer. Even though the treatment helps the patient fight cancer, it can have negative consequences to sleep.
The study measured sleep, depression and circadian rhythms both before and after treatment. Higher rates of insomnia persisted even beyond completion of treatment.
It is important for caregivers to think of the patient as a whole, including their diagnosis, sleep history and how sleep patterns have changed.
Q. What treatments are available to help cancer patients sleep better?
Your physician may prescribe a sleep aid. Sometimes low-dose antidepressants, anticonvulsants or antipsychotic medications are also prescribed. Or, there are medications to increase melatonin, such as ramelteon.
Cognitive behavioral therapy for insomnia (CBTI) is a multi-session sleep treatment program to address sleep-incompatible behaviors, such as drinking caffeine before bed, as well as how a person can anticipate and better cope with the worry of not getting enough sleep. CBTI also focuses on sleep hygiene, or the best habits to get good sleep.
Another non-medication treatment is the use of bright light therapy, as studies have reported that exposure to bright light at certain times of the day improves sleep.
Q. What is coming in the future to help cancer patients with sleep issues?
Chronotherapy is a growing field of research that aims to optimize cancer treatments by integrating information about an individual's circadian rhythm in the design of anticancer drug delivery. That means delivering chemotherapy, for example, at certain times of the day depending on the individual’s circadian rhythms rather than the hospital or staff’s schedule. Bright light therapy may also be more effective for certain people at certain times of the day.
Possible outcomes to cancer patients are milder nausea, improved quality of life, higher doses with fewer side effects, less fatigue and longer survival.
Sleep Tips
- Use a sleep diary to track your patterns
- Put away e-readers, tablets and other devices at night
- Light therapy boxes should be at least 10,000 lux, similar to a bright sunny day
- Ask your doctor about ways to improve sleep hygiene
- See your doctor if insomnia occurs three or more times per week or persists for three months
Read the Summer, 2015 issue of Thrive.