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April 11, 2019

“Super sleeper”- Idiopathic hypersomnia 

Idiopathic hypersomnia (IH) is characterized by chronic excessive daytime sleepiness, prolonged nighttime sleep, and sleep inertia, but with normal hypocretin-1 and no cataplexy². IH is a rare disorder (estimated prevalence 20-50 per million) and typical onset occurs between 10-30 years of age¹. Differential diagnosis includes narcolepsy, obstructive sleep apnea, insufficient sleep syndrome, Kleine-Levin Syndrome, and hypersomnolence associated with psychiatric and medical disorders. Multiple sleep latency test (MSLT) shows decreased sleep latency of <8 minutes, no or <2 sleep-onset rapid eye movement periods (SOREMPs), and > 11 hours of total sleep time on 24 hours polysomnography¹. Patients with narcolepsy have low hypocretin-1, and two or more SOREMPs on MSLT¹. Unlike in narcolepsy, nocturnal sleep and daytime naps are typically long and nonrestorative. There are no FDA approved medications for treating IH, and stimulants such as modafinil, methylphenidate or dextroamphetamine are used to control excessive day time sleepiness. 

References

1. International classifications of sleep disorders. (2014). American Academy of Sleep Medicine, 3^rd ed. ISBN:0991543408 

2. Winkelman, J.W., Henderson, J.H., Kotagal, S., Lee-Chiong, T.L., Lichstein, K.L., Murray, B.J., & Schenck, C.H. (2008). Case Book of sleep medicine- A learning companion to the international classification of sleep disorders. American Academy of Sleep Medicine. ISBN: 978-0-9657220-4-9. 

Submitted by Prava Karki, MS-4, Caribbean Medical University and Faisal Khan, MD, DABSM, DABPN, Consultant Neurologist, Sugar Land Neurology and Sleep, Texas 

Prava Karki and Dr. Khan report no disclosures.