ORIGINAL ARTICLE Assessment of the relationship between postural stability and sleep quality in patients with fibromyalgia Nuray Akkaya & Semih Akkaya & Nilgun Simsir Atalay & Merve Acar & Necdet Catalbas & Fusun Sahin Received: 11 June 2012 / Revised: 18 October 2012 / Accepted: 28 October 2012 / Published online: 21 November 2012 # Clinical Rheumatology 2012 Abstract The aim of this study is to investigate the rela- tionship of postural stability and sleep disorders in patients with fibromyalgia syndrome. Frequency of falls in the last 6 months in 48 fibromyalgia and 32 control subjects were recorded. Postural stability was assessed by static posturog- raphy device (Tetrax, Sunlight Medical Ltd., Israel). Func- tional assessment consisted of lower-body strength; one-leg stance test were applied to all subjects. Fibromyalgia impact questionnaire (FIQ), sleep quality numeric rating scale (NRS), and Pittsburgh Sleep Quality Index were inquired. The number of falls in the last 6 months was significantly higher in the fibromyalgia group. Mean total value of sta- bility indexes was 201.7±70.9 vs. 162.6±29.6 in fibromy- algia and control subjects (p <0.05). NRS and Pittsburgh Sleep Quality Index were significantly higher in fibromyal- gia patients. It was detected that there were significant relationships between fall risk and NRS scores (r 0 0.565), and FIQ fatigue subscores (r 0 0.560) (both p <0.05). Worse postural performance and fall risk found in the fibromyalgia patients compared to controls were related with the sleep quality in the last 24 h and level of fatigue. Keywords Fatigue . Fibromyalgia syndrome . Postural stability . Sleep quality Introduction Fibromyalgia syndrome (FMS) is a chronic widespread pain syndrome, with the main symptoms are fatigue, depression, and sleep disorders [1]. Although the most striking symp- tom is pain, other sensorimotor functions might also be affected from the abnormal central processes [2]. Balance, or postural stability, is a complex task that involves the integration of multiple sensory inputs to exert appropriate neuromuscular activity required to maintain the balance. In a study of 2,596 fibromyalgia patients, 45 % of them had balance problems, and these balance problems were among the first ten common symptoms [3]. A recent study demonstrated increased postural instability and in- creased frequency of fall in FMS patients [4]. Abnormal pain processing by the central nervous system is thought to lead to increased pain and fatigue, as well as to the deterioration of proprioceptive inputs from painful muscles to the central nervous system, and increased fall risk due to sleep disturbance-related postural instability in FMS patients [2, 5]. It was suggested that postural stability which includes multiple neural subsystems might be affect- ed in FMS, and fatigue, decreased flexibility, and greater body mass index may have a role in postural instability [4]. It is well known that fatigue-induced cognitive dysfunc- tion and sleep disturbances have negative impacts on bal- ance in healthy people [6, 7]. Restless sleep, non-REM sleep disturbances, and fatigue are common symptoms of FMS [8]. Although the relationship of sleep disorders and postur- al instability is well studied in healthy people [6, 7], it has not been studied in FMS, in which sleep disorders and postural instability are common. The aim of the study was to compare the static postural stability and fall risk between FMS patients and control subjects, as well as to investigate the relationships of the static postural stability, sleep quality, and functional status. N. Akkaya (*) : N. S. Atalay : N. Catalbas : F. Sahin Department of Physical Medicine and Rehabilitation, Pamukkale University Medical School, 20210 Kınıklı Denizli, Turkey e-mail: nrakkaya@gmail.com S. Akkaya Department of Orthopedics and Traumatology, Pamukkale University Medical School, 20210 Kınıklı Denizli, Turkey M. Acar Department of Physical Medicine and Rehabilitation, Denizli Government Hospital, Bayramyeri Denizli, Turkey Clin Rheumatol (2013) 32:325–331 DOI 10.1007/s10067-012-2117-y