Nocturnal sleep, daytime sleepiness and fatigue in fibromyalgia patients compared to rheumatoid arthritis patients and healthy controls: A preliminary study

Abstract

Objective

Fibromyalgia (FM) and rheumatoid arthritis (RA) are pain disorders, both of which are associated with complaints of sleep disturbance, non-refreshing sleep, and daytime sleepiness and fatigue. Given the putative differential central versus peripheral nervous system involvement in these disorders, subjective and objective measures of nocturnal sleep, daytime sleepiness, fatigue and pain were compared between patient groups and to healthy controls (HC).

Methods

Fifty women (18 with FM, 16 with RA, and 16 HC) completed an 8 h nocturnal polysomnogram (NPSG), Multiple Sleep Latency Test (MSLT) the following day, and self-reports of sleepiness, fatigue, and pain.

Results

FM and RA patients were similar to each other and had less total sleep time than HC, primarily due to more wake after sleep onset. In an analysis of sleep and wake bouts, both patient groups had longer duration of wake bouts than HC. Nocturnal sleep was judged to be non-restorative for both patient groups. Although reporting the greatest subjective sleepiness and fatigue, FM patients had less objective (MSLT) daytime sleepiness than HC, whereas RA patients were intermediate in objective sleepiness. Unlike the RA and HC, FM patients also showed no association between their subjective and objective sleepiness.

Conclusions

Women with FM have similar nocturnal sleep disturbance as those with RA, but FM patients report greater self-rated daytime sleepiness and fatigue than RA and HC, which did not correspond to the relatively low level of objectively determined daytime sleepiness of FM patients. These findings suggest a generalized hyperarousal state in FM.

Introduction

The first polysomnographic (PSG) study of fibromyalgia (FM) was performed in 1975 [1]. This early PSG study of FM reported intrusions of EEG alpha activity (α-EEG) in NREM sleep, which correlated positively with pain scores. This data led to the speculation that α-EEG is a marker of the musculoskeletal pain and mood symptoms of FM. Subsequently, there have been multiple reports indicating a correlation between α-EEG and FM pain [2], [3], [4], [5]. While FM continues to be characterized by sleep disturbance and pain, the causal link between α-EEG and FM symptoms has not been substantiated. The presence and amount α-EEG is difficult to assess and quantify visually and the procedures and scoring rules for its visual assessment have yet to be established [6], [7]. Automated, fast Fourier transform computer analyses of α-EEG is also not without controversy [8]. Furthermore, the α-EEG NREM sleep anomaly is reported in other patient populations, as well as healthy controls (HC) [9], [10], [11], [12], [13]. In fact, some have argued that the non-specificity of the α-EEG marker is because α-EEG is a characteristic of sleep maintenance rather than disturbance [8], [9], [10], [11], [12], [13], [14].

Beyond the α-EEG anomaly, FM patients also have significantly longer sleep latencies than healthy controls (HC) [12]. They often have increased arousals and a greater number of transitions from one sleep stage to another [15] and lower amounts of slow wave sleep (corrected for age), REM, and total sleep time (TST) [16]. Shorter durations of stage 2 NREM sleep have also been reported, compared to healthy controls (HC) [17]. FM patients often report insomnia symptoms [2], [4], [18] and their reports of not getting enough sleep, disturbed sleep, and waking less rested are more frequent than in HC. Interestingly, they have better recall of their awakenings than controls [3].

Similar to FM, rheumatoid arthritis (RA) patients experience sleep disturbance and pain [7]. However, the sleep disturbance of RA has been characterized by fragmented sleep and increased wake caused by discrete, short arousals [19], [20]. RA patients were also found to have multiple stage shifts and a higher occurrence as compared to HC of periodic leg movements, which also fragment sleep. [21], [19]. Patients with RA often report daytime sleepiness and fatigue in association with their pain [22]. The Level of fatigue is an important symptom as it has been shown to correlate with dysfunction [23]. A recent study of RA showed that poor sleep quality was significantly correlated with mood disturbance, pain, fatigue and functional disability [24]. Studies of RA patients have also shown that hypnotic treatment (triazolam) of sleep disturbance can lead to a reduction in morning stiffness and daytime sleepiness [25]. In contrast, similar hypnotic treatment (zopiclone) only improves “tiredness” in FM patients [26].

FM is thought of to involve heightened sensitivity of all, in addition to pain, central nervous system sensory processing, or in abnormalities of the endocrine system [16], whereas RA is more frequently attributed to peripheral nervous system and immune system dysfunction [7]. The pain of FM is considered to be widespread involving all soft tissues [16], while that of RA is localized to the joints and surrounding tissue [7]. The similarity of symptoms, despite the difference between relative central and peripheral involvement and localization of pain in these two disorders, makes them valuable to compare to further understand the relation of nocturnal sleep to daytime sleepiness, fatigue and pain. The authors of a literature review on sleep in RA argued that current studies of chronic rheumatoid diseases are inconsistent in their findings and they encouraged the further systematic, objective study of sleep and daytime function [22].

We report on the relation between self-report measures and objective measures of nocturnal sleep (PSG) and daytime sleepiness (MSLT), as well as self-reported fatigue and pain in these two pain disorders. We compared the two pain disorders to each other and to healthy age and gender matched controls. Symptoms of sleepiness, fatigue, and pain are commonly reported in both disorders and are associated with reports of disturbed and non-refreshing sleep. To our knowledge, no studies have compared objective measures of the sleep of FM to RA patients directly. In addition, there are no studies that have compared patients’ subjective and objective measures of sleepiness, as well as attempted to distinguish sleepiness from fatigue in these pain disorders.