Chronic Fatigue Syndrome and How It Affects Sleep

This article discusses what chronic fatigue syndrome is, its negative effect on sleep, and research that is being done on this syndrome.

For people with chronic fatigue syndrome, sleep problems are common. Sleep disorders and disruptive and non-refreshing sleep are some of the most frequent complaints from people suffering from chronic fatigue. Chronic fatigue syndrome is a debilitating medical condition. It's also a mysterious -- and historically controversial -- illness.

The basic characteristics of chronic fatigue syndrome include ongoing fatigue that interferes with daily activities, problems with memory and concentration, muscle pain and headaches, and other physical symptoms such as sore throat and tender lymph nodes. People with chronic fatigue also experience feelings of malaise after periods of mental and physical exertion.

The causes of chronic fatigue are unknown. There is no test to determine the presence of the illness. Physicians make a diagnosis based on the presence of a cluster of symptoms over an extended period of time, at least six months, and by ruling out other conditions. For many years, chronic fatigue was considered with skepticism by some in the medical community. There were those who questioned whether chronic fatigue was an illness at all, rather than the consequence of a sleep disorder or a mental health issue. Over the past two decades, chronic fatigue syndrome has won acceptance by the medical establishment. But much about the disorder -- its causes, its mechanisms in the body -- remain largely unknown.

Disrupted sleep is a hallmark of chronic fatigue syndrome. Chronic fatigue is associated with a range of sleep problems, including:

• Excessive daytime sleepiness
• Non-restorative sleep (waking feeling tired even after sufficient or prolonged periods of rest)
• Difficulty falling asleep and staying asleep
• Sleep disorders such as obstructive sleep apnea, insomnia, and narcolepsy

Despite the frequency with which people with chronic fatigue syndrome experience sleep disturbances, the connection between sleep and chronic fatigue -- like so much else about the disorder -- is not well understood.

Researchers at Australia's Victoria University have conducted a review of research related to sleep and chronic fatigue. Their analysis sheds some light on possible reasons for poor sleep among patients with chronic fatigue.

Sleep complaints are common among chronic fatigue patients, but there is no single or typical sleep experience for people with this disorder. For the past two decades, research has shown high levels of sleep disorders among adults with this condition:

• Several studies, including this one, have found that more than half of chronic fatigue patients have some type of sleep disorder.
• This study showed chronic fatigue patients experience greater levels of disrupted sleep than patients with multiple sclerosis.
• More than 50 percent of chronic fatigue patients in this study had obstructive sleep apnea or sleep-related movement disorders, such as restless leg syndrome.
• A similar study showed 46 percent of chronic fatigue patients suffered from obstructive sleep apnea
• This large, population-based study showed nearly 80 percent of chronic fatigue patients experienced un-refreshing sleep, and 20 percent had obstructive sleep apnea or narcolepsy.

An important area of research into the connection between sleep and chronic fatigue looks at the role of pain. The physical pain associated with chronic fatigue may be a significant factor in the sleep problems experienced by people with chronic fatigue. We know that pain and sleep influence each other in multiple ways. Pain can make sleep difficult to achieve and sustain. Lack of sleep, in turn, can make us more sensitive to pain. Studies like this one have shown that pain causes chronic fatigue patients to wake more often throughout the night than either healthy people or those with depression. And one study found that disruption to slow wave sleep in healthy people triggered physical pain and fatigue similar to people with chronic fatigue syndrome. As researchers themselves note, the role of muscle pain in sleep disorders among chronic fatigue sufferers is an area of research that warrants more attention and further study.

There's another body of research that suggests that people with chronic fatigue experience changes to their sleep cycles that could result in less restorative sleep. Studies have shown that people with chronic fatigue may spend less time in slow wave sleep than healthy people. Slow wave sleep occurs during the sleep stages three and four and is the most restorative sleep we can experience. Studies have shown that chronic fatigue patients spend a reduced amount of time in slow wave sleep and in REM sleep than healthy people. To date, there is less evidence for the reduction in REM sleep than in slow wave sleep. The cause of this disturbance to sleep cycles is unclear. However, there is evidence of a possible link between systematic inflammation and disruptions to sleep cycles, particularly to time spent in slow wave sleep. Systemic inflammation in the body is common among chronic fatigue patients and may play a role in the persistent problem of non-refreshing sleep.

Still another area of study suggests that changes to the body's nervous system activity may play a role in the sleep disruptions experienced by people with chronic fatigue. Chronic fatigue patients experience alterations to the functioning of their nervous systems during waking hours, and these can continue during sleep. Several studies have shown that chronic fatigue patients are more likely to experience disruptions to normal nervous system activity during sleep, and this may be affecting the quality of sleep they experience.

There are so many questions that remain unanswered about the relationship between sleep and chronic fatigue syndrome. Why and how does non-restorative sleep occur so frequently? What is the cause -- or effect -- of sleep disorders such as obstructive sleep apnea and restless leg syndrome among people with chronic fatigue? Do the standard measurements of sleep quality work accurately for this group of people?

Here's one thing we do know: Sleep disruptions are a critical component of chronic fatigue syndrome. Answering these and other questions about the role that sleep plays in chronic fatigue could provide some much needed insight into this debilitating illness.

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