Sleepy Kids: are the current diagnostic criteria for multiple sleep latency tests enough?

Excessive daytime sleepiness (EDS) is common in childhood and is currently quantified using adult criteria on a multiple sleep latency test (MSLT). This study aimed to describe paediatric MSLT results, particularly focussing on a previously proposed alternative mean sleep latency (MSL) threshold for children of 12 min, and assess the impact of a 5th nap. We performed a retrospective analysis of MSLTs at a single paediatric centre from 2004 to 2021. Narcolepsy was defined as a mean sleep latency (MSL) ≤8min with ≥2 sleep onset REM (SOREM) periods. Idiopathic Hypersomnia (IH) was defined as a MSL ≤8min with <2 SOREMs. An ambiguous MSLT result was defined as a MSL 8-12min and/or ≥2 SOREM periods. Of 214 MSLTs [50 % female, median age 14.0y (range 3.3-20.1y)], narcolepsy was diagnosed in 48 (22 %), IH in 22 (10 %) and the result was ambiguous in 44 (21 %). Those with ambiguous MSLT results were older (15.6 vs 13.4y, p = 0.006) with a higher proportion of females (61 % vs 35 %, p = 0.01) in comparison to the narcolepsy group. A 5th nap was performed in 60 (28 %) of MSLTs and only changed the outcome in one case. In conclusion, MSLT results are borderline in 21 % of paediatric cases, suggesting that current adult diagnostic criteria may miss narcolepsy and IH in children. A 5th nap usually makes no difference or increases the MSL, suggesting that a four nap MSLT protocol could be used apart from rare cases where the result is borderline after the 4th nap.