Home Polysomnography Reveals a First-Night Effect in Patients With Low Sleep Bruxism Activity

To examine the presence of a first-night effect (FNE) and the level of internight variability in sleep bruxism (SB) activity when a self-applicable electrode set is used in home polysomnography (PSG) in a sample of subjects with possible SB.

Fourteen females and two males aged 38.3 ± 9.1 years (mean ± standard deviation) with self-reported SB underwent home-PSG on three consecutive nights. The subjects applied PSG sensors themselves, including self-applicable electrode sets used to record sleep and masseter muscle activity. Repeated-measures analysis of variance was used to compare SB and sleep variables between the nights.

Surprisingly, there were statistically significant elevations in the rhythmic masticatory muscle activity (RMMA) episode index (P = .009), burst index (P = .016), and bruxism time index (P = .049) throughout the course of 3 nights. More bruxers were diagnosed on the second (6 bruxers, ≥ 2 episodes/h) and third night (7 bruxers) compared to the first night (2 bruxers). Most subjects (14/16) had their highest RMMA index on the second or third night. The mean coefficient of variation for RMMA episode index was 50.7%. No statistically significant differences were detected in other sleep variables.

The results indicate that a FNE may be present in SB activity, possibly lasting several nights in some subjects. Furthermore, FNE appears to be combined with high internight variability of SB activity without indications of internight changes in sleep macrostructure. To confirm the level of ongoing SB activity, several nights of PSG may be required, especially in subjects with low first-night SB activity.

A commentary on this article appears in this issue on page 1281.