According to the National Fibromyalgia Research Association, more than 75 percent of Fibromyalgia (FM) patients complain of sleep disturbances and fatigue. Studies have shown that this is often the result of problems FM sufferers have falling asleep and staying asleep. While some people don't remember waking up frequently, others do recall these disruptions to a good night's rest. Either way, these abnormal sleep patterns prevent FM sufferers from getting a healthy amount of restful, restorative sleep.

Fibromyalgia's Connection to Impaired Deep Sleep

There are five stages of sleep, and in the course of a normal night's rest, a person will normally cycle through various stages, from light to deep to dreaming, every 90 minutes or so. Dreaming occurs during what's called REM (rapid eye movement) sleep. Interestingly, EEG (brain wave) studies have found that FM patients lack the restorative levels of deep, non-REM sleep. It is during these deepest levels of sleep - also known as stages 3 and 4 - that the body restores and refreshes itself. Stage 3 is characterized by moderately deep sleep and stage 4, the deepest sleep phase, is when certain substances like growth hormones are released for body-tissue repair and replenishment.

Research suggests that people with FM are constantly aroused by bursts of "awake" brain activity, which limits the amount of time they spend in these critical deep stages of sleep.

"On EEG studies, FM patients in deep-sleep stages have been found to have alpha waves, which are signs of arousal or wakening,"

Says Patrick Wood, MD, chief medical advisor for the National Fibromyalgia Association. One study published in the Journal of Rheumatology found that patients experience at least twice as many arousals per hour as people without the disorder.

Fibromyalgia's Constant "Fog" and Fatigue

The lack of uninterrupted deep sleep may be the reason why people with are also plagued by extreme daytime fatigue. In today's world, many people complain of feeling tired, but the exhaustion associated with is much more severe. patients report feeling as if their bodies have been completely drained of energy, which can lead to limited physical and mental functioning.

It's also common for people with to have problems with concentration, thinking, and memory, a condition known as "fibro fog." A recent University of Michigan study found that people with FM exhibit memory impairments on tests that can mimic 20 years of aging. One possible reason: Memories are processed during sleep stages 3 and 4.

"During these two stages of sleep, the brain sorts through information accumulated during the day, taking it out of short-term memory and putting it into long-term memory,"

Says Dr. Wood. When the amount of deep sleep is reduced, experts speculate that the body may have a limited ability to repair and replenish the brain's functioning, affecting memory as well as energy.

Brain Chemicals: The Root of the Problem?

While the causes of sleep problems in those with are not yet completely understood, new findings are uncovering possible links. One theory is that brain chemicals may be out of whack.

"There's very good evidence that is associated with abnormal amounts of dopamine, which is an energy-related neurotransmitter, or brain chemical,"

Says Dr. Wood. Norepinephrine, another energizing neurotransmitter, and cortisol, a hormone associated with stress, have also been found to be abnormal in patients. In addition to interfering with restful sleep, neurochemical and hormonal imbalances may exacerbate the pain associated with, in the opinion of some experts. Others researchers believe that it's the constant pain that triggers deep-sleep abnormalities.

More studies are currently underway that may help uncover more definitive causes of sleep difficulties associated with this painful, life-altering condition. It is hoped that in the next five years or so scientists will have more answers about the connection between and disordered sleep.