Orthostatic Intolerance, Autonomic Dysfunction in Children With Hypersomnia

Female student sleeping on desk
This retrospective study assessed the presence of orthostatic intolerance in pediatric patients with primary hypersomnia disorders soon after diagnosis.

One-third of 89 children and adolescents diagnosed with primary hypersomnia disorders had symptoms of orthostatic intolerance (OI) around the time of initial sleep diagnosis, researchers found in a study published in Sleep Medicine.

OI is a common sign of autonomic dysfunction, which can impair quality of life. Additionally, the treatment of hypersomnia often requires the use of stimulant medications, which may increase dizziness and palpitations that patients with OI experience. Study researchers sought to determine the prevalence and characteristics of OI in pediatric patients with hypersomnia disorders because these features had not been the focus of a systematic examination.

Study researchers identified 89 pediatric patients with hypersomnia disorders (46 with narcolepsy type 1, 17 with narcolepsy type 2, 18 with idiopathic hypersomnia, 7 with hypersomnia related to medical disorders, and 1 with Klein Levin syndrome) who had been evaluated at the Center for Sleep Medicine at the Mayo Clinic.

They conducted an autonomic reflex screen testing composed of a quantitative sudomotor axon reflex test, orthostatic blood pressure and heart rate response to 70 (degrees) head-up tilt, heart rate response to deep breathing and the Valsalva maneuver, and beat-to-beat blood pressure responses to the Valsalva maneuver. Results were quantified with the Composite Autonomic Severity Score (CASS), in which points are given for adrenergic, sudomotor, and cardiovagal impairment.

33 patients (girls, 22; boys, 11; mean age at diagnosis, 14.5 years) had a history of OI, and it was not more prevalent in any hypersomnia type (P =.47). About 75% of the patients with OI reported dizziness and fatigue around the time of the diagnosis of the sleep disorder, and 46% complained of headache.

About half of them became symptomatic during the tilt table test. 5 patients had heart rate changes significant enough to diagnose postural orthostatic tachycardia syndrome (POTS), and 8 had abnormal CASS scores (>1), including 2 who had moderate autonomic impairment.

25 patients were either not receiving neurologic/psychoactive medications or had stopped taking them for at least 72 hours prior to the testing. The group without symptoms of OI had a 1:2.1 ratio of girl to boy patients (P =.0015 by Chi-square test).

The study researchers recommended inquiring about symptoms of orthostatic intolerance at the time of the initial hypersomnia diagnostic evaluation, before starting medications.

Limitations of the study included its retrospective nature, a referral bias because patients undergoing autonomic testing were selected based on the presence of orthostatic symptoms, and that actigraphy was not obtained systematically.

“Once treatment for hypersomnia has begun with central nervous system stimulants, selective serotonin-reuptake inhibitors or tricyclic agents, the evaluation of autonomic function may become masked,” and distinguishing OI-related fatigue from sleepiness when hypersomnia patients return for follow-up may become difficult, study researchers concluded.


Jagadish S, Singer W, Kotagal S. Autonomic dysfunction in childhood hypersomnia disorders. Sleep Med. 2021;78:43-48. doi:10.1016/j.sleep.2020.11.040