Influence of a Post-Test Factor on the Results of the Multiple Sleep Latency Test

Study objectives: The multiple sleep latency test (MSLT) is the standard method for the objective measurement of excessive daytime sleepiness. It is well established that preceding factors may influence the MSLT result. Aim of this study was to evaluate the potential influence of a post-test factor on the MSLT outcome.

Methods: For this retrospective study we reviewed polysomnography (PSG) reports conducted between 2012 and 2013. PSG reports including MSLT with at least four runs were included. Patients were stratified into (1) those discharged immediately after the MSLT or (2) those discharged on the following day. For further analysis, we categorized the patients into three subgroups according to mean MSLT sleep latency: < 5, 5-9.9, and 10-19.9 minutes, corresponding to a pathological, borderline, and normal MSLT result.

Results: A total of 2,749 PSG records were reviewed; 262 included MSLT and 241 met inclusion criteria for the study. Of those, 152 patients were discharged immediately after the last MSLT run, 89 on the following day. MSLT mean sleep latency, and sleep latency of the last run only, did not differ between both groups (p = 0.070 and p = 0.065). In the subgroup of patients with pathological MSLT, there was a trend towards prolonged sleep latency in the last run in patients discharged immediately after the test (p = 0.055).

Conclusions: Our findings suggest that the MSLT post-test factor of discharge timing has no major impact on the MSLT outcome.