Can EEG spectral analysis distinguish children with narcolepsy from those with idiopathic hypersomnia and subjective sleepiness?

EEG spectral analysis provides a more sensitive measure of sleep disruption than conventional sleep macro-architecture. We aimed to examine the use of this technique applied to overnight polysomnography in distinguishing children with narcolepsy and idiopathic hypersomnia (IH) from subjectively sleepy children with a non-diagnostic multiple sleep latency test. The relative power was calculated for delta (0.5-3.9 Hz), theta (4-7.9 Hz), alpha (8-11.9 Hz), sigma (12-13.9 Hz), and beta power (14-30 Hz). A mean value for each frequency was calculated for each 30 s epoch then averaged for each sleep stage within each child. Data are presented as median and interquartile range. Twenty-eight children with narcolepsy, 11 with IH, and 26 with subjective sleepiness were included and individually matched for age and sex with a control child. In N2, the F4 beta power was lower in the narcolepsy compared with the IH group (p < 0.05). The F4 theta power was higher in the narcolepsy compared with the subjectively sleepy group during wake (p < 0.001), N2 (p < 0.01), N3 (p < 0.05), and total sleep (p < 0.01). During total sleep the F4 delta power was lower in both the narcolepsy and IH groups compared with the subjectively sleepy group (p < 0.05 for both). Our study identified specific EEG frequencies which differed between groups of children referred for assessment of EDS. In particular, differences in theta and delta power in children with narcolepsy and IH compared with others with subjective sleepiness may provide insights into the pathophysiology associated these conditions.