Lower Serotonin Levels in Severe Sleep Bruxism and Its Association with Sleep, Heart Rate, and Body Mass Index

Background: Sleep bruxism (SB) is a complex behaviour that seems to be associated with the serotoninergic pathway.

Objectives: This exploratory research aimed to evaluate the levels of serotonin in individuals with sleep bruxism diagnosed by video polysomnography. The study also evaluated whether the levels of serotonin were associated with body mass index, heart rate, and sleep parameters.

Methods: The study participants were adults hospitalised in the Department and Clinic of Internal Medicine, Occupational Diseases, Hypertension and Clinical Oncology at the Wroclaw Medical University. They underwent a single-night video polysomnography during which sleep and SB parameters and heart rate were evaluated. Additionally, body mass index and blood serotonin levels were evaluated for each patient.

Results: A total of 105 patients were included in this study (80 women and 25 men). All the patients were Caucasians aged 18-63 years, with a mean age ± (standard deviation) of 33.43± 10.8 years. Seventy-five patients (71.43%) presented sleep bruxism (bruxism episodes index ≥2) and 30 (28.57%) did not. Fifty patients (47.62%) presented severe sleep bruxism (bruxism episodes index >4). The results showed that lower blood serotonin levels were associated with severe sleep bruxism; increased bruxism episodes index, rapid eye movement sleep, and body mass index; and decreased maximal pulse.

Conclusion: Severe sleep bruxism and the associated phenomena seem to co-occur with lower blood serotonin levels. The study supports the hypothesis on the relationship between the serotoninergic pathway and sleep bruxism.