Altered circadian patterns of diurnal blood pressure in clinical phenotypes of bruxism: A pilot study on autonomic imbalance in healthy young adults

BACKGROUND: Bruxism, a repetitive masticatory muscle activity, is increasingly recognized as a behavioral marker with possible systemic implications. While its association with autonomic dysregulation has been proposed, the relationship between bruxism phenotypes and variations in circadian blood pressure (BP) in healthy individuals remains unclear. OBJECTIVES: The aim of the study was to explore whether distinct behavioral bruxism phenotypes (sleep vs. awake, morning vs. evening) are associated with altered diurnal BP profiles, particularly postprandial patterns, in healthy normotensive young adults. MATERIAL AND METHODS: A total of 59 healthy young adults (mean age: 23.4 ±3.8 years) with probable bruxism were classified into 4 phenotypes: sleep bruxism (SB); morning awake bruxism (AB); evening AB; and undefined. The participants underwent 3 standardized BP measurements throughout the day (morning, postprandial and afternoon), alongside assessment using the Pittsburgh Sleep Quality Index (PSQI), the Insomnia Severity Index (ISI) and the Epworth Sleepiness Scale (ESS). Bruxism classification was based on self-reports, clinical signs and timing patterns. Data was analyzed using analysis of variance (ANOVA) and post hoc tests. Confidence intervals and effect sizes were calculated, and boxplots were used to illustrate group differences. RESULTS: Participants with SB exhibited a significantly steeper postprandial diastolic BP decline compared to other phenotypes (p = 0.045), deviating from the expected parasympathetic post-meal dip observed in healthy profiles. Sleep bruxism was also associated with poorer sleep quality (higher PSQI scores), greater insomnia severity (higher ISI scores) and a lack of significant increase in daytime sleepiness. Individuals with morning AB showed a biphasic BP pattern suggestive of autonomic lability, while participants with evening AB exhibited a blunted profile. Questionnaire data reinforced a chronic hyperarousal profile among SB participants. CONCLUSIONS: Behavioral bruxism phenotypes, particularly SB, may reflect underlying autonomic imbalance and altered circadian BP modulation, even in clinically normotensive individuals. These findings support the hypothesis that bruxism may serve as a behavioral marker of subclinical cardiovascular risk. Further studies incorporating objective autonomic markers and longitudinal data are warranted.