Is there a first night effect on sleep bruxism? A sleep laboratory study

Area of Science:

• Sleep Medicine
• Neurology
• Dentistry

Background:

• Sleep bruxism (SB) is a common condition characterized by involuntary jaw muscle activity during sleep.
• The frequency and severity of sleep bruxism can fluctuate over time, making accurate assessment challenging.
• The 'first-night effect' (FNE) is a phenomenon where sleep patterns differ on the first night in a laboratory setting compared to subsequent nights.

Purpose of the Study:

• To investigate the presence and impact of the first-night effect on sleep bruxism (SB) parameters.
• To determine if sleep laboratory recordings over two consecutive nights reveal significant changes in SB activity.
• To assess the clinical implications of the first-night effect for diagnosing and managing sleep bruxism.

Main Methods:

• A retrospective analysis of polysomnographic (PSG) data from 16 sleep bruxism patients (17-39 years old) recorded over two consecutive nights.
• Quantification and comparison of sleep parameters and rhythmic masticatory muscle activity (RMMA) variables between the first and second nights.
• Patients were categorized into low and moderate-high frequency RMMA groups based on episode and burst counts per hour.

Main Results:

• No significant first-night effect was observed for overall sleep variables or the RMMA episode index.
• However, significant time and group interactions were found for total sleep time, sleep efficiency, and stage transitions.
• The second night showed significantly higher burst index, bruxism time index, and mean burst duration; five low-frequency patients shifted to moderate-high frequency.

Conclusions:

• The first-night effect does not significantly alter the severity of rhythmic masticatory muscle activity (RMMA) frequency in young, healthy sleep bruxism (SB) patients.
• A single night of sleep recording may suffice for assessing moderate-to-high frequency sleep bruxism (SB) in clinical practice.
• For patients with low RMMA frequency, a second night of recording, combined with medical and dental history, may be necessary for accurate assessment.