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Feeling tired, sleepy or fatigued may be signs of an underlying sleep disturbance. Other clues include snoring, waking up at night, morning headaches or difficulty concentrating. Poor sleep can affect a person’s quality of life, reduce productivity, lead to accidents (by falling asleep at the wheel) and worsen underlying neurological conditions (such as myasthenia gravis).
Sleep disturbances may be caused by insomnia, restless legs or sleep disordered breathing. Insomnia is constant difficulty falling asleep or remaining asleep. Restless legs syndrome is a condition where there is the need to move one’s legs to relieve unpleasant sensations, which can affect sleep. Sleep disordered breathing includes obstructive sleep apnea, central sleep apnea and hypoventilation. Obstructive sleep apnea is due to upper airway muscle weakness, where there is a temporary stop of airflow of more than 90% of normal for at least 10 seconds (measured during a sleep study). Obstructive sleep apnea is more common in older adults who are overweight, smoke and drink excessive amounts of alcohol. Central sleep apnea is caused by weakness of the chest wall muscles and diaphragm, which is made worse by muscle relaxation that occurs during sleep. Of concern is that people with sleep disordered breathing are at higher risk for stroke. It is estimated that 25-30% of American adults have a sleep disturbance. Previous studies have suggested that sleep disturbances are more common in people with myasthenia gravis.
Sleep disturbances in patients with myasthenia gravis are not well understood. It is not clear if sleep disturbances are related to the myasthenia gravis; medications used to treat myasthenia gravis or are due to treatable sleep disturbances (such as excessive caffeine or energy drink use and herbal supplements) that are unrelated to myasthenia gravis.
Subjective sleep disturbances (symptoms that patients report) can be recorded using 6 sleep related questionnaires. The Pittsburgh Sleep Quality Index evaluates how good sleep is or any sleep disturbances over the last month. It records sleep information such as usual bed time and rising time. The Epworth Sleepiness Scale looks at daytime sleepiness. It consists of questions about how likely a person would doze off during certain activities. The Penn State Worry Questionnaire asks about the worry level with worry-related questions in different situations. The Beck Depression Inventory addresses the existence and severity of depression using depressionrelated questions in different situations. The Insomnia Severity Index measures the severity of insomnia. The Restless Legs Syndrome Questionnaire rates the symptoms of restless legs syndrome.
It is unknown how often sleep disturbances occur in myasthenia gravis. There are no clear guidelines on how to treat insomnia, fatigue and daytime sleepiness in myasthenia gravis.
At the University of California-Irvine ALS and Neuromuscular Center, we are currently completing a study in Sleep Disturbances in Myasthenia Gravis. Our preliminary results suggest that subjective sleep disturbances are common in our subjects with myasthenia gravis. Twothirds of our study subjects have poor sleep quality, using the results of these 6 sleep related questionnaires. We are now looking to see if there is an association between the sleep disturbances and the symptoms and medications in subjects with myasthenia gravis.
Acknowledgement: Dr. Wang would like to acknowledge Dr. Marcel Hungs from the Neurologic Associates of St. Paul and the University of Minnesota, her neurology colleagues from UCI and Dat Le (Junior Specialist) at UCI for their work on the research study “Sleep Disturbances in Myasthenia Gravis”. The study is supported by a research grant from the Myasthenia Gravis Foundation of California.