Variation in the Low-frequency Fluctuation of the Cortex Among Patients with Paradoxical Insomnia: A Resting-State Functional Magnetic Resonance Imaging Study

Background: Paradoxical insomnia is one of the most prevalent subtypes of insomnia disorder and its symptom includes a discrepancy between subjective and objective sleep measures. Objectives: This study aimed to evaluate the amplitude differences of low-frequency fluctuation as a possible local characteristic in paradoxical insomnia by resting-state functional MRI among patients with paradoxical insomnia and healthy subjects. Methods: A t-test was used in this case-control study to investigate possible changes in low-frequency fluctuation amplitude in 15 paradoxical insomnia patients and 48 healthy subjects. Results: The results were far from the chance level by removing nuisance variables and controlling for multiple comparisons. In addition, there was a decrease in the amplitude of low-frequency fluctuation among people with paradoxical insomnia compared to the healthy group in the right region of the superior parietal lobule and precuneus regions. Conclusions: Based on these results, brain signals appear to play an important role in the pathophysiology of paradoxical insomnia, and further research may identify the mechanism behind this type in the future.