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J Clin Sleep Med. 2013 Nov 15;9(11):1139-45. doi: 10.5664/jcsm.3152.

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

Author information

1
Department of Dentistry and Oral Surgery, Hyogo College of Medicine, Nishinomiya City, Hyogo, Japan ; Faculté de medicine dentaire, Université de Montréal, Montréal, Canada ; Centre d'étude du Sommeil et des Rythmes Biologiques, Hôpital du Sacré-Coeur de Montréal, Montréal, Canada.

Abstract

STUDY OBJECTIVES:

Sleep bruxism (SB) is reported to vary in frequency over time. The aim of this study was to assess the first night effect on SB.

METHODS:

A retrospective polysomnographic (PSG) analysis was performed of data from a sample of SB patients (12 females, 4 males; age range: 17-39 years) recorded in a sleep laboratory over 2 consecutive nights. Sleep parameters and jaw muscle activity variables (i.e., rhythmic masticatory muscle activity [RMMA]) for SB were quantified and compared between the 2 nights. Subjects were classified into groups according to severity of RMMA frequency, such as low frequency (2-4 episodes/h and/or < 25 bursts/h) and moderate-high frequency (≥ 4 episodes/h and ≥ 25 bursts/h).

RESULTS:

Overall, no first night effects were found for most sleep variables. However, total sleep time, sleep efficiency, and stage transitions showed significant time and group interactions (repeated measures ANOVAs, p ≤ 0.05). The RMMA episode index did not differ between the 2 nights, whereas the second night showed significantly higher burst index, bruxism time index, and mean burst duration (repeated measure ANOVAs, p ≤ 0.05). Five patients of 8 in the low frequency group were classified into the moderate-high frequency group on the second night, whereas only one patient in the moderate-high frequency group moved to the low frequency group.

CONCLUSIONS:

The results showed no overall first night effect on severity of RMMA frequency in young and healthy patients with SB. In clinical practice, one-night sleep recording may be sufficient for moderate-high frequency SB patients. However, low RMMA frequency in the first night could be confirmed by a second night based on the patient's medical and dental history.

KEYWORDS:

Sleep bruxism; first night effect; polysomnography; rhythmic masticatory muscle activity; sleep laboratory

PMID:
24235894
PMCID:
PMC3805798
DOI:
10.5664/jcsm.3152
[Indexed for MEDLINE]
Free PMC Article

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