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.

Normal multiple sleep latency test values in adults: A systematic review and meta-analysis.

Sleep latency is a measure of time it takes to enter sleep. Very short sleep latencies are indicative of excessive daytime sleepiness and pathological sleep conditions such as narcolepsy. The normal range of mean sleep latency calculated from the multiple sleep latency test in healthy adults is not well-established. We provide a review of normative mean sleep latency values on the multiple sleep latency test by synthesizing data from 110 healthy adult cohorts. We also examine the impact of demographic variables such as age, sex, body mass index, sleep architecture and sleep-disordered breathing as well as methodological variables such as sleep onset definitions and multiple sleep latency test protocols. The average mean sleep latency was 11.7 min (95% CI: 10.8-12.6; 95% PI: 5.2-18.2) for cohorts evaluated using 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. There were no significant associations between mean sleep latency and demographic or methodological variables. A negative association of -0.29 per one unit increase (95% CI: -0.55 to -0.04) was found between mean sleep latency and apnea-hypopnea index on prior night polysomnography. Establishing updated ranges for mean sleep latency among healthy adults may guide clinical decision-making surrounding sleep pathologies and inform future research into the associations between patient variables, daytime sleepiness, and sleep pathologies.

Prevalence of objective excessive daytime sleepiness in a cohort of patients with mild obstructive sleep apnea.

STUDY OBJECTIVES: Obstructive sleep apnea (OSA) is common, yet the relationship between mild OSA and excessive daytime sleepiness (EDS) is unclear. Our objective was to determine the prevalence of objective EDS in a population with mild OSA using the mean sleep latency (MSL) from the multiple sleep latency test (MSLT). METHODS: We retrospectively analyzed 1205 consecutive patients who underwent a polysomnography and a following day MSLT at a single sleep center. Adult patients who met criteria for mild OSA with an apnea-hypopnea index of 5 to <15 events/h were identified, and the percentage of patients with a MSL ≤ 8 min was determined. Sleep study and demographic variables were examined to evaluate predictors of objective EDS. RESULTS: Of 155 patients with mild OSA, objective EDS was found in 36% (56/155) with an average MSL of 5.6 ± 2.1 min in the objectively sleepy patients. Objectively sleepy patients with mild OSA had greater total sleep time (411.6 ± 48.9 vs. 384.5 ± 61.7 min, p = 0.004), increased sleep efficiency (84.9 ± 9.7 vs. 79.7 ± 12.7%, p = 0.01), and decreased wake after sleep onset time (53.0 ± 36.9 vs. 67.4 ± 46.1 min, p = 0.04) compared to patients with mild OSA but without objective EDS, with total sleep time being an independent predictor of MSL (p = 0.006). The Epworth Sleepiness Scale (ESS) weakly correlated with objective EDS (ρ = - 0.169, p = 0.03). CONCLUSIONS: There is a large subgroup of patients with mild OSA patients who have objective sleepiness. This may represent an ideal subgroup to target for future studies examining the effect of treatment in mild OSA. Additionally, the ESS was a poor predictor of this subgroup with mild OSA and objective EDS.

Test-Retest Reliability of Two Consecutive Mean Sleep Latency Tests in Patients with Hypersomnia.

Reliability of mean sleep latency testing (MSLT) over consecutive days in patients with hypersomnia is unknown. We reviewed MSLTs of patients with hypersomnia without cataplexy who underwent our two consecutive MSLT protocol (N=29). Average MSLs were 10.9 and 10.9 minutes for days 1 and 2, respectively. Agreement for pathological hypersomnia (defined as MSL≤8 minutes) between MSLT days showed k=0.85 for all (N=29) and k=0.76 for those without sleep apnea (N=20). In patients with subjective complaints of hypersomnia, a single MSLT is sufficient (vs. addition of 2nd day MSLT) in the setting of carefully implemented protocol controlling for potential confounding variables.

Narcolepsy presenting as schizophrenia: a literature review and two case reports.

Schizophrenia is a psychiatric disorder that causes significant disability and morbidity. Narcolepsy is a disorder, less prevalent than schizophrenia, but a disorder in which symptoms overlap with schizophrenia. This overlap in symptoms can cause narcolepsy to be confused with schizophrenia. The differences and similarities between narcolepsy and schizophrenia are discussed in the context of two cases. The first case describes an adolescent and the second case describes a refractory case of narcolepsy that did not respond to stimulants. Both cases were previously diagnosed as schizophrenia and did not respond to trials of antipsychotics and other psychotropics. The patients were reevaluated and referred to sleep testing at our facility for clinical suspicion of narcolepsy. Both patients underwent polysomnography with subsequent multiple sleep latency testing. The sleep testing results and multiple sleep latency testing criteria for narcolepsy are also discussed. The patients were treated for narcolepsy resulting in remission of the psychotic symptoms with significant behavioral improvement. We recommend that psychiatrists consider narcolepsy in the differential diagnosis when faced with refractory psychosis.