Arousal burden is highest in supine sleeping position and during light sleep

Arousal burden (AB) is defined as the cumulative duration of arousals during sleep divided by the total sleep time. However, in-depth analysis of AB related to sleep characteristics is lacking. Based on previous studies addressing the arousal index, we hypothesized that the AB would peak in the supine sleeping position and during non-rapid eye movement stage 1 and show high variability between scorers.

Nine expert scorers analyzed polysomnography recordings of 50 participants, the majority with an increased risk for obstructive sleep apnea. AB was calculated in different sleeping positions and sleep stages. A generalized estimating equation was used to test the association between AB and sleeping positions, sleep stages, and scorers. The correlation between AB and arousal index was tested with Spearman's rank-order correlation.

AB significantly differed between sleeping positions (P < .001). The median AB in the supine sleeping position was 47-62% higher than in the left and right positions. The AB significantly differed between the sleep stages (P < .001); the median AB was more than 200% higher during non-rapid eye movement stage 1 than during other sleep stages. In addition, the AB differed significantly between scorers (P < .001) and correlated strongly with arousal index (r = .935, P < .001).

AB depends on the sleeping position, sleep stage, and scorer, as hypothesized. AB behaved similarly to the arousal index, but the high variability in the ABs between scorers indicates a potential limitation caused by subjective manual scoring. Thus, the development of more accurate techniques for scoring arousals is required before AB can be reliably used.

Pitkänen M, Huovinen J, Rissanen M, et al. Arousal burden is highest in supine sleeping position and during light sleep. J Clin Sleep Med. 2025;21(2):337-344.