We found a prevalence rate of 9.2% for RLS, which was similar to other studies, but it was slightly higher than in Fereshtehnejad et al.'s study in Iran. This variation was expected as his study was population-based (
4,
6). Other studies have reported prevalence rates ranging from 5.5% to 11% in adult Caucasian populations, whereas prevalence rates are lower for Asian populations, ranging from 1% to 7.5% (
25). In the Eastern Mediterranean WHO region, only one study with a sample size (n = 2,682) reported a prevalence rate of 8.4% in the general population in Saudi Arabia (
26).
According to our research findings, RLS was slightly more prevalent in men, while women exhibited higher severity of RLS symptoms. However, previous studies have shown inconsistent results, with some reporting a higher prevalence in females — up to twice as much — and others finding no gender differences. These observations diverge from earlier research on Saudi Arabian (
26) and Turkish populations (
27).
Our results demonstrated an increase in sleep latency and a decrease in total sleep time and sleep quality. The RLS is recognized for disrupting sleep patterns and quality. The RLS patients often struggle to fall asleep and stay asleep, leading to fragmented sleep, insomnia, and excessive daytime sleepiness (
1,
13). According to the ESS, The present study failed to show an increase in daytime sleepiness. Conditions like RLS or periodic limb movement disorder may disrupt sleep quality without necessarily affecting daytime drowsiness measured by ESS. It is essential to consider potential factors when interpreting the relationship between RLS and ESS scores in Iranian patients.
Our results showed that as the RLS score increased, the scores for mood disorders, including depression, anxiety, and stress, also increased significantly. In the study by Sevim et al., patients with RLS were found to have much higher levels of anxiety and depression symptoms compared to the control subjects. Additionally, a possible link between the severity of RLS and the severity of anxiety and depression symptoms was observed (
9). Similarly, Winkelmann's study indicated a clear association between RLS and a higher risk of depression and anxiety, as well as more severe anxiety/depression scores. Individuals with RLS had a higher lifetime prevalence of major depressive and panic disorder compared to those without RLS symptoms. The odds ratios indicated a strong association between panic disorder and RLS. These findings suggested the need for increased awareness of the mental health implications of RLS (
8).
A study of 317 psychiatric inpatients found a prevalence of RLS at 16.4%, significantly higher than the estimated 5 - 10% in the general population. The severity of RLS was rated as moderate to severe according to the IRLSSG (
28). Another study reported that the prevalence of RLS was higher in patients using antidepressants compared to the general population. Additionally, patients who received combined drug treatment had a 4.7-fold increase in RLS (
29).
Electroencephalogram (EEG) studies have shown differences in brain function between patients with RLS and controls, suggesting a dissociated vigilance in RLS similar to changes seen in major depression. Dopamine agonists have been effective in reducing symptoms of both RLS and depression, indicating a potential role of dopaminergic dysfunction (
30). Treating mood disorders in RLS patients is challenging. Selective serotonin reuptake inhibitors (SSRIs) can exacerbate RLS symptoms due to their effects on serotonin levels in the brain, which can influence motor activity. Antidepressants with dopaminergic effects might provide relief for RLS symptoms (
16). For patients experiencing depression or anxiety disorders alongside RLS, healthcare providers may consider a careful combination approach that includes both antidepressants and dopamine agonists.
In our sleep clinic, 11 patients were diagnosed with restless symptoms in organs other than the legs, with the majority of these patients being female. Understanding rare variants of RLS is crucial for accurately diagnosing diseases. The literature contains numerous case reports about these variants (
31), highlighting the importance of recognizing that this condition is not limited to leg symptoms. These variants can be challenging to diagnose due to their atypical presentations. A thorough clinical history and symptom assessment are crucial.
The present study had some limitations. First, the study's cross-sectional nature limits its ability to establish causality between RLS and mood or sleep disorders. Second, the study is limited to a single sleep clinic registry in Iran, which may limit the generalizability of the findings to broader populations. Lastly, the lack of objective measures may introduce reporting bias. Incorporating objective measures like actigraphy could enhance diagnostic accuracy.
We recommend for future research the conduction of longitudinal studies to better establish causality between RLS and associated mood or sleep disorders. Expanding research to include multiple sleep clinics across different regions or countries could improve the generalizability of the findings. Utilizing objective measures such as actigraphy, polysomnography, or neurophysiological assessments in future studies is also recommended.
5.1. Conclusions
The RLS significantly affects individuals’ mental health factors, including sleep quality, insomnia score, depression, anxiety, and stress. Understanding how various classes of antidepressant drugs interact with RLS is vital for optimizing treatment strategies for patients experiencing both mood disorders and sleep disturbances associated with RLS. It is essential to note that restlessness resembling RLS can manifest in various parts of the body.