Key Insights into Multiple Sleep Latency Test Norms Using Large-Scale Data: Mark I. Boulos, MD, BSc, FRCP, CSCN, MSc

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“The purpose of this study was to perform a larger and pretty comprehensive meta-analysis on the mean sleep latency derived from the MSLT (Multiple Sleep Latency Test). We also wanted to look at the impact of things like age, sex, body mass index, other sleep metrics. In addition, we wanted to investigate different methodological variables, such as sleep onset definitions, and sleep study features, as well other markers preceding the sleep study and see if that did affect the mean sleep latency on the MSLT that was performed.”

In the last 2 decades, research has helped propel the knowledge and understanding of narcolepsy type 1 (NT1) and type 2 (NT2), otherwise known as narcolepsy with or without cataplexy.¹ Diagnosing this sleep disorder is based on a combination of clinical information with polysomnography and the multiple sleep latency test (MSLT), which have been noted to be moderately reliable at diagnosing NT1 but not NT2.²

In a new systematic review and meta-analysis published in Sleep Medicine, findings showed a longer average of mean sleep latency among healthy adults using a more updated later definition of sleep onset compared with previous definition.³ Among 110 cohorts involving 4058 healthy adults, the average mean sleep latency was 11.7 min (95% CI, 10.8–12.6; 95% PI, 5.2–18.2) for the studies assessed with the earlier definition of sleep onset and 11.8 min (95% CI, 10.7–12.8; 95% PI, 7.2–16.3) for those evaluated using the later definition.

Senior author Mark I. Boulos, MD, BSc, FRCP, CSCN, MSc, associate professor, department of medicine, division of neurology, Institute of Medical Science, University of Toronto, recently sat down in an interview with NeurologyLive® to discuss why establishing normal mean sleep latency is important for clinicians and sleep specialists when diagnosing sleep disorders such as narcolepsy. He talked about the factors that were considered in the comprehensive meta-analysis to determine the average mean sleep latency in the MSLT. Additionally, Boulos spoke about how the study's findings on normal mean sleep latency align with previous research, and the implications it has for clinicians.

REFERENCES
1. Barateau L, Pizza F, Chenini S, Peter-Derex L, Dauvilliers Y. Narcolepsies, update in 2023. Rev Neurol (Paris). 2023;179(7):727-740. doi:10.1016/j.neurol.2023.08.001
2. Torstensen EW, Haubjerg Østerby NC, Kornum BR, et al. Repeated polysomnography and multiple sleep latency test in narcolepsy type 1 and other hypersomnolence disorders. Sleep Med. 2023;110:91-98. doi:10.1016/j.sleep.2023.07.029
3. Iskander A, Jairam T, Wang C, Murray BJ, Boulos MI. Normal multiple sleep latency test values in adults: A systematic review and meta-analysis. Sleep Med. 2023;109:143-148. doi:10.1016/j.sleep.2023.06.019