Greater insights into the mechanisms and consequences of sleep and sleep disorders have been achieved through advances in brain imaging methods that describe various aspects of neural function. These are collectively referred to as functional neuroimaging. These include techniques such as PET, fMRI, single-photon emission computed tomography (SPECT), transcranial sonography, magnetoencephalography (MEG), low-resolution brain electromagnetic tomography (LORETA), and combined methods such as combined EEG and fMRI. Extensive applications of brain imaging have been made to help clarify the changes in regional brain function that result from perturbations in either homeostatic or circadian processes, and also have clarified the relationship between these brain changes and the behavioral consequences of these disruptions. The earliest applications of neuroimaging to the study of sleep disorders were those of functional neuroimaging methods to study the global brain states of waking, NREM, and REM sleep. Brain imaging studies have been utilized in narcolepsy and the hypersomnias.

Hypersomnia is characterized by recurrent episodes of excessive daytime sleepiness (EDS) or prolonged nighttime sleep that affects the everyday life of the patient. Clinical surveys have reported EDS as a complaint in up to 68% of normal high-school children. Causes of EDS are divided into three categories: insufficient nighttime sleep, fragmented nighttime sleep, and an increased need of sleep. Pediatric daytime sleepiness scale (PDSS) is a recently introduced validated measure for assessing sleepiness in children. Management of disorders that may coexist with hypersomnia of central origin such as obstructive sleep apnea, psychiatric disorders, medications, and circadian rhythm disorders will require specific therapeutic interventions, but need to be done for optimal outcome in children with narcolepsy. The general approach to the treatment of childhood narcolepsy and other hypersomnias of central origin is based on the adult experience.