Newsletter Article

Cancer & Sleep

February 2017

Cancer patients and cancer survivors often report sleep problems, specifically relating to their sleep time and sleep efficiency.[1] Studies suggest that 35-50% of cancer patients suffer from insomnia, compared to 15% of the normal population. A patient is considered to have insomnia if it takes 30 minutes or more to fall asleep, if he or she experiences 30 minutes or more of nighttime awakenings, or both. Sleep efficiency, which is the ratio of total sleep time to time spent in bed, must also be 85% or less. This must occur at least three nights per week and cause impairment of daytime functioning or significant stress. Even if patients don’t fit every criterion, decrease in effective sleeping can still result in a decrease in quality of life and may play a role in physical symptoms.[2]

Compared to control subjects, cancer survivors show significantly lower sleep efficiency scores.[3] This lower sleep efficiency was associated with lower mental and physical quality of life scores. Cancer survivors were also more sedentary than control subjects, which also correlated with lower mental and physical quality of life scores.

A study measured sleep duration and quality using wrist-worn actigraphs on women who were diagnosed with advanced breast cancer.[4] The objective was to determine if sleep efficiency had an effect on the women. Better sleep efficiency was shown to predict a significant reduction in mortality. This was still significant even when controlling for other factors like age, cancer treatment, metastatic spread, etc. The data also showed that less wake after sleep onset, fewer wake episodes, and shorter wake episode duration also contributed to decreases in mortality.

Research shows that lung cancer patients have the poorest sleep quality compared to other cancer patients.[5] A study measuring sleep quality and functional assessment in lung cancer patients found that sleep efficiency was positively associated with functional assessment scores. They also found that wake after sleep onset was negatively associated functional assessment scores.

Sleep is an important aspect of our lives, and it can alter our quality of life and how we repair our bodies. Quality sleep is even more important for those with cancer who may be fighting for their lives.


Grapefruits were first discovered in Barbados in the 18th century, and they are now widely available in many parts of the world. They were not a naturally occurring fruit, but rather the result of crossbreeding between an orange and a pomelo. Tart and tangy in taste, grapefruits are available in ruby, pink, and white varieties, and they are at their most flavorful throughout the winter and in early spring.

All grapefruits are an excellent source of vitamin C, but the red and pink varieties also contain the antioxidant lycopene.[6] Among other common carotenoids, lycopene has the highest capacity to help the body fight free radicals. Lycopene is specifically linked to a reduction in the risk of developing prostate cancer. Another group of health-promoting compounds found in grapefruits are called limonoids. These help to inhibit tumor growth by promoting the formation of a specific detoxifying enzyme. This enzyme causes a reaction in the liver that helps make toxic compounds more water soluble, and thus more easily excreted.

Because grapefruit or grapefruit juice can decrease certain enzyme activity in the liver, it can affect how some drugs interact with the body.[7] These enzymes will normally break down medication at a predictable rate, but when they are blocked, certain drugs can reach dangerously high levels. These include some statins, antibiotics, cancer drugs, and heart drugs. Even though grapefruits are nutritious and delicious, it may be best to talk with your doctor before eating grapefruit or drinking grapefruit juice if you are on any medication.

Ceviche with Mint and Grapefruit

1 Ruby Red grapefruit
1/2 red onion, thinly sliced (1/2 cup)
1/2 serrano chile, thinly sliced
1 cup fresh mint, thinly sliced
1/4 cup fresh lime juice (from 2 to 3 limes)
1 teaspoon coarse salt
1/2 pound sea scallops, tough muscles removed, cut into 1/4-inch-thick rounds, or 1/2 pound sushi-grade yellowtail (hamachi), cut into 1/4-inch-thick slices
Micro mint, for garnish


Cut away peel and pith from grapefruit. Cut along membranes, releasing segments into a medium nonreactive bowl; reserve juice in bowl. Using a slotted spoon, transfer 1/2 of the segments to a cutting board; dice. (Reserve remaining segments for another use.) Transfer diced segments to a large nonreactive bowl. Strain reserved juice into a glass measuring cup. Pour 1/4 cup of the juice into the large bowl, reserving remaining juice for another use.

Add onion, chile, mint, lime juice, salt, and scallops or yellowtail to grapefruit mixture. Gently stir until well combined. Cover with plastic wrap, and refrigerate for 2 hours. (Do not refrigerate for more than 2 hours; the scallops and yellowtail will become tough.)

Drain mixture, reserving liquid. Divide onion, chile, mint, and scallops or yellowtail among 4 serving plates. Garnish with micro mint, and drizzle with reserved liquid. Serve immediately.

Recipe from

Cable vs. Selectorized Machines

Most gyms are equipped with a variety of resistance machines that offer different physical benefits. Two major types of weight machines are cable-based or selectorized machines. Selectorized machines are typically designed for one type of movement, and the user is most often seated in the machine. Cable-based machines offer a greater range of motion and require more stabilization from supporting muscle groups.

A study measured the EMG level of specific muscle groups when performing several exercises on either a selectorized or cable machine.[8] Subjects performed bicep curls, chest presses, and overhead shoulder presses. Greater EMG levels were seen when performing the exercises on a cable machine. Pectorals and deltoids showed higher EMG levels during bicep curls; biceps, deltoids, and obliques for the chest press; and biceps and obliques for the overhead shoulder press. There was also a greater range of motion recorded during the cable exercises compared to the selectorized exercises. A greater range of motion can increase the amount of time under tension and cause more microtears in the muscles, both of which can lead to increased muscle mass and strength.

Both cable-based and selectorized equipment offer benefits and can be used effectively. However cable machines may offer more benefits by activating supporting muscles at a higher rate than selectorized machines. This may lead to faster improvements at the gym and may possibly translate better to activities of daily living.

Health Matters is written by Lindsey Guthrie, MS, RD, LD/N and Tyler Guthrie, MS, CSCS.


  1. OncoLink. Sleep Problems (Insomnia) in the Cancer Patient.
  2. Ancoli-Israel S. Sleep Disturbances in Cancer: A Review. Sleep Medicine Research. 2015; 6(2): 45.
  3. Rafie C, Ning Y, Wang A, Houlihan R. Relationship of physical activity and sleep quality to quality of life among cancer survivors: findings of the day and night study. American Institute for Cancer Research 2016 Research Conference. 2016.
  4. Palesh O, Adridge-Gerry A, Zeitzer JM, et al. Actigraph-Measured Sleep Disruption as a Predictor of Survival among Women with Advanced Breast Cancer. Sleep. 2014; 37(5): 837.
  5. Dean GE, Abu Sabbah E, Yingrengreung S, et al. Sleeping with the enemy: sleep and quality of life in patients with lung cancer. Cancer Nursing. 2015; 38(1): 60.
  6. The World’s Healthiest Foods. Grapefruit.
  7. WebMD. Drugs That Interact With Grapefruit on the Rise.
  8. Signorile JF, Rendos NK, Vargas H, et al. Differences in Muscle Activation and Kinematics Between Cable-Based and Selectorized Weight Training. Journal of Strength and Conditioning. 2017; 31(2): 313.

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