Objective: To clarify whether there is impaired melatonin secretion and whether it is associated with sleep disturbance in patients with multiple system atrophy (MSA).

Background: Previously, we measured salivary melatonin levels in patients with Parkinson’s disease (PD) and found that in these patients, daytime sleepiness was associated with higher melatonin levels during the day. We also found that peak melatonin secretion, which is usually observed at night while sleeping, occurs in early evening or even during the day in patients with PD and that this secretion abnormality is related to PD sleep disorder. Various types of sleep disturbance, such as insomnia, interrupted sleep, and decrease in sleeping time, are observed in patients with MSA. However, the association between sleep disturbance and melatonin secretion in MSA is not well known.

Methods: This study included 12 patients with MSA and 13 age and sex-matched controls. Salivary melatonin levels were measured using enzyme-linked immunosorbent assay; saliva samples were noninvasively collected in the morning (8–9 AM), during the day (2–3 PM), and before sleep. We used the Parkinson’s Disease Sleep Scale (PDSS) for assessing nighttime sleep disturbance and the Epworth Sleepiness Scale (ESS) for assessing daytime sleepiness. The association between salivary melatonin levels and the PDSS and ESS scores was evaluated.

Results: There were no significant differences in the ESS scores and PDSS scores between MSA and controls (ESS: 3.8 vs 4.2, PDSS: 115 vs 116). Salivary melatonin levels in the morning and in the day did not show significant differences between the groups. But 5 out of 12 MSA patients showed paradoxically increased salivary melatonin levels in the day, which were normally suppressed and the melatonin levels before sleep were lower in MSA than controls (5.0 ng/ml vs 10.2 ng/ml, p < 0.05). There were no correlations between ESS or PDSS scores and salivary melatonin levels in the morning, in the day and before sleep in both groups.

Conclusions: Since melatonin levels before sleep were lower in patients with MSA than in controls and paradoxically increased salivary melatonin levels during the day were observed in some of the patients with MSA, disordered sleep may be associated with melatonin secretion abnormality in MSA; thus, further studies on specific types of sleep disorders are necessary. The association between melatonin levels and ESS and PDSS scores differed from those we obtained from our study on PD; therefore, it is essential to accumulate a larger number of cases.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/association-of-impaired-melatonin-secretion-with-sleep-disturbance-in-multiple-system-atrophy/