Fibromyalgia Syndrome (FMS) and Chronic Fatigue Syndrome (CFS) are both multifactoral, debilitating disorders that affect a significant portion of the general population. Many of the abnormal findings detected in patients with FMS and CFS are associated with poor sleep, including fatigue, pain, depressed mood, and memory deficits. We know that sleep, pain, and fatigue are very closely linked, but what role does non-restorative sleep (NRS) play in these syndromes?
NRS is characterized by feeling unrefreshed upon waking, despite sleeping an adequate number of hours, and may also be coupled with daytime impairment, pain, fatigue, and electroencephalogram (EEG) arousals in non-REM sleep. In the 1970s, researchers began looking at NRS as a possible cause for FMS and CFS, as NRS is common among these patients. NRS is also a primary symptom of insomnia and common among patients with organic sleep disorders, such as sleep apnea. Presently, NRS does not have a uniform definition, a known cause, or successful treatment options, but it may give us some valuable insight into the importance of sleep for chronic pain and fatigue.
The idea of NRS stems from the restorative sleep theory, where brain activity during sleep is thought to restore the body and mind for daily activity. This is supported by the knowledge that skin renewal and bone growth occur at a faster rate during sleep in rats and humans. Furthermore, higher metabolic demands in humans lead to longer sleep duration. Despite our current knowledge, NRS is still poorly understood and not well-defined in the medical research. Since NRS is a marker for pain, sleep, alertness, and mood, proper definitions can help in the diagnosis and treatment of all of these health issues.
For sufferers of FMS and CFS, NRS is one of the primary complaints. In a study of FMS patients, 65.7% reported NRS.1 A similar study of adolescent CFS patients found that 100% of the study population reported “non-refreshing sleep”, as opposed to 10% of the control group.2 CFS patients have also been found to be 28 times more likely to score positively on a NRS related factor than healthy control participants.3 Empirical data supports the idea that FMS and CFS are strongly associated with NRS, but as there is no longitudinal data on this issue, we have yet to determine whether NRS precedes FMS/CFS, or vice versa. What’s more, there is no definitive treatment for FMS or CFS, so it is unknown whether NRS would resolve once FMS/ CFS is successfully treated.
Overall, NRS plays an important role in many chronic conditions involving fatigue, pain, cognition, and mood, such as FMS and CFS. NRS is often confused with sleep fragmentation and deprivation, and remains hard to quantify. More research needs to be done in order to definitively understand the relationship between NRS and FMS/CFS. For now, general sleep hygiene guidelines, such as maintaining a daily routine and avoiding caffeine close to bed time, should be followed in order to maximize restorative sleep.
Meriem Mokhtech, BS
Senior Laboratory Technician
UF Center for Musculoskeletal Pain Research
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- Knook L, Kavelaars A, Sinnema G, Kuis W, Heijnen CJ. High nocturnal melatonin in adolescents with chronic fatigue syndrome. J Clin Endocrinol Metab 2000;85(10):3690–2.
- Unger ER, Nisenbaum R, Moldofsky H, et al. Sleep assessment in a population-based study of chronic fatigue syndrome. BMC Neurol 2004;4:6.
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