A recent study found that fatigue in multiple myeloma patients is associated with sleep and mood disturbances, reduced abilities to complete simple physical activities, and elevated levels of physical pain.

The study also finds, however, that pain is not as directly linked to fatigue as sleep, the ability to carry out physical activity, and, especially, mood disturbances. 

Instead, pain's impact on fatigue may be indirect, through its influence on sleep, mood, or overall physical condition.

Based on their findings, the study authors conclude that physicians need to work harder with patients to control the forces that lead to patient fatigue.  The authors note, for example, that even limited amounts of exercise can improve a patient's strength and stamina enough to have a noticeable impact on fatigue.

Disturbances in sleep patterns and insomnia are very common among patients with cancer and can lead to cancer-related fatigue. 

In multiple myeloma, this is further compounded by the fact that nearly 100 percent of patients experience anemia (low red blood cell levels), which contributes to fatigue, during the course of their disease. 

Bone pain, which can disrupt sleep, also is a common challenge for myeloma patients, and many myeloma-related medications either disrupt sleep patterns or directly cause fatigue in many patients.

In the recent study, researchers from the University of Arkansas for Medical Sciences and two other U.S. universities explored how strongly fatigue in myeloma patients is associated with sleep patterns, mood, pain, and the ability to carry out physical activity.

The study included 187 newly diagnosed patients with an average age of 56 years. A bit more than half of the study participants (58 percent) were male, and one-third had advanced myeloma at the time of diagnosis.

Based on two commonly used measures of fatigue, the researchers found that one out of every five patients had signs of severe fatigue at the beginning of the study.  Severe fatigue was more common among the women in the study, with almost a third of all female patients showing signs of severe fatigue.

The total sleep time per day averaged 8.5 hours per patient. However, the study authors pointed out that a rather high 20 percent of the total sleep time per patient was daytime sleep.

The researchers also measured a number of other patient characteristics that might be linked to fatigue.  Patients answered questions about how much physical pain they are experiencing.  For several nights during the study, each patient wore a wristwatch-like device that recorded sleep patterns.  Patient strength and stamina were tested using exercise weights and by recording how far patients could walk in a specific amount of time.

In addition, a standardized survey was used to measure how much each patient was experiencing mood disturbances.

Using the data they collected, the researchers found that pain and mood disturbances are strongly associated with increased fatigue, while patient strength and stamina are strongly associated with decreased fatigue.

Somewhat surprisingly, the researchers initially did not find much of an association between fatigue and different measures of sleep.  There was not, for example, a statistically significant association between fatigue levels and the average number of hours patients slept each night.

The study authors, however, did further statistical tests to determine which factors are particularly associated with fatigue.  Those tests confirmed that the quantity and quality of sleep are important in determining a patient's fatigue levels.

The more detailed statistical analysis also suggested that patient physical condition and mood are tightly connected to fatigue, but pain is not.  Mood, in particular, appears to be a "significant individual contributor" to fatigue, the study authors note in their article.

The study results suggest that the connection between pain and fatigue in myeloma patients may not be as direct as often assumed.  Instead, the connection may be indirect.  Pain may increase the chance of mood disturbances and reduce a patient's ability to be physically active.  Those factors, in turn, may then create the fatigue commonly associated with myeloma-related pain.

For more information, please see the article in Cancer Nursing (abstract).