This study offers the preliminary objective evidence that cyclosporine improves nocturnal sleep quality in patients with moderate-to-severe AD analyzed by objective procedures. Cyclosporine is potentially associated with improved quality of life in patients with moderate-to-severe AD through the favorable effects on sleep.
From the perspective of each patient, cyclosporine significantly improved at least one of the seven parameters in eight of the 12 examined patients. Case 3 did not show a remarkable improvement compared to other cases, although class II topical corticosteroid treatment was started at the initiation of cyclosporine administration. From the perspective of each parameter, cyclosporine significantly improved sleep efficiency in seven patients and wake after sleep onset in six patients. On the other hand, cyclosporine significantly improved mean values of sleep efficiency and sleep latency, although it did not significantly improve mean values of the other parameters. These observations suggested that (i) cyclosporine can shorten the time until onset of sleep in bed, resulting in better sleep efficiency; and (ii) cyclosporine may not always contribute to relieve the difficulty falling asleep in terms of onset of sleep discontinuation. Overall, cyclosporine is strongly suggested to improve sleep quality in patients with moderate-to-severe AD, which might be explained by two possible mechanisms: (i) cyclosporine reduces pruritus, which impairs sleep quality; and (ii) cyclosporine regulates the cytokines/chemokines associated with sleep.
Sleep quality in patients with AD has been evaluated by various subjective tools. Silverberg et al. examined sleep disturbance in patients with AD by a cross-sectional questionnaire of 34,613 adults and reported that eczema was associated with fatigue [odds ratio (OD), 2.97], regular daytime sleepiness (OD, 2.66), and regular insomnia (OD, 2.36) [16], roughly in line with a study reported by Li et al. in which sleep disturbance was observed in most adult patients with AD [17]. Ramirez et al. studied 13,988 children, including 4938 children with AD, by using questionnaires, and reported that nighttime awakenings, regular early morning awakenings, difficulty falling asleep, and nightmares were detected in 15–65% of children with AD, although total sleep duration was similar between children with active AD and without AD [18]. Thus, the previous studies demonstrated that AD definitely impairs subjective sleep quality. On the other hand, our data objectively showed that cyclosporine administration significantly improved sleep latency but not total sleep time. Cyclosporine might be ineffective on the improvement of total sleep time in this study, because the total sleep time of our patients was not originally impaired by AD only.
As it is known that pruritus impairs sleep quality in patients with AD [10], Kaaz et al. analyzed the impact of pruritus on sleep quality among 100 patients with AD and indicated a substantial association with insomnia [19]. Several recent studies have reported that patients with inadequately controlled AD exhibit a higher burden of pruritus, as well as more frequent sleep disturbance, including longer sleep latency and increasing needs of over-the-counter sleep medications compared to patients with controlled AD [20, 21]. On the other hand, there is limited direct evidence to show the effects of cyclosporine on both sleep and pruritus concurrently in patients with AD; moreover, those effects were evaluated with subjective tools. Sowden et al. reported that cyclosporine administration significantly improved concurrently both loss of sleep and pruritus; (i) each VAS score of loss of sleep was 13.8 and 41.9 in cyclosporine-treated patients and placebo-treated patients, respectively, and (ii) each VAS score of pruritus was 16.6 and 51.2 in cyclosporine-treated patients and placebo-treated patients, respectively [22]. This report provides high-quality but vague evidence of sleep quality improvement by cyclosporine in patients with AD. In addition to that, our study potentially provides the specific information that cyclosporine administration improves sleep efficiency and sleep latency in patients with moderate-to-severe AD.
Cyclosporine alleviates pruritus, potentially by inhibiting pruritus-inducing cytokines such as interleukin (IL)-4, IL-13, and IL-31, and by ameliorating peripheral nerve abnormalities and skin barrier dysfunction [23, 24]. These facts strongly support the hypothesis that the favorable effects of cyclosporine on sleep quality in patients with AD are responsible for improvement of pruritus. On the other hand, some cytokines associated with AD directly impair sleep quality. IL-4, IL-10, and IL-13 have been reported to decrease NREM sleep amount [25]. Khattri et al. suggest that cyclosporine reduces expression of type 2 T helper cell (Th2)-related molecules, including IL-4 in patients with AD [23]. Such mechanisms for cyclosporine may contribute to the improvement of sleep quality (Fig. 3). However, cytokines that regulate NREM sleep including tumor necrosis factor-α, interferon-α, IL-1β, IL-2, and IL-6 can also be negatively modulated by cyclosporine in patients with AD [25, 26]. Moreover, the mechanisms of sleep quality improvement by cyclosporine through sleep-associated cytokines/chemokines still cannot be easily understood, as suggested by Xerfan et al. [27]. Therefore, more studies are required to evaluate the effects of cyclosporine on sleep-associated cytokines/chemokines.
For patients with moderate-to-severe AD, systemic immune-modulating treatments including cyclosporine and dupilumab are indicated. Cyclosporine is sometimes preferentially selected as the systemic therapy for patients with AD rather than dupilumab, because (i) the efficacy of cyclosporine for clinical signs of AD has been repeatedly and sufficiently confirmed in multiple clinical trials over the past 20 years [28]; (ii) cyclosporine is usually cheaper than dupilumab; and (iii) the duration of cyclosporine administration is shorter than dupilumab. In addition to aforementioned reasons, this study potentially shows a merit of cyclosporine which improves sleep quality in patients with moderate-to-severe AD.
Some limitations of this study must be considered. First, the therapeutic options other than cyclosporine were not completely controlled before or after cyclosporine administration; in particular, topical corticosteroid treatment was added for case 3 at the initiation of cyclosporine administration. Second, the data on the severity of eruptions and pruritus were lacking after the initiation of cyclosporine administration; such data are important to obtain a clearer understanding about changes in sleep quality. Third, the number of examined patients was relatively small, which may impair the reliability of the data. Fourth, the sleep analyses were performed within 1 month after the initiation of cyclosporine. However, Haw et al. reported that during longer-term cyclosporine administration, effects appeared during the 6-month follow-up period [29]. Therefore, if our analyses were performed at later time points after the initiation of cyclosporine administration, better results would have been demonstrated. Fifth, the selection bias in this study should be considered due to referred patients. Ideally, the patients with AD who are referred to the dermatology clinic should be recruited.