While the pathophysiology of idiopathic hypersomnia is unknown, emerging science suggests that nighttime sleep dysfunction may contribute to daytime sleepiness in patients with idiopathic hypersomnia. A systematic review and meta-analysis that included 10 studies found that, on average, several sleep architecture hallmarks were different in patients with idiopathic hypersomnia relative to controls.

• Total sleep time and percent of REM sleep were increased in patients with idiopathic hypersomnia compared with controls.
• Sleep-onset latency and percent of slow-wave sleep were decreased in patients with idiopathic hypersomnia compared with controls.
• Sleep efficiency and REM latency were similar between patients with IH and controls.

In addition to nighttime sleep dysfunction, other physiological changes have been observed in some patients with idiopathic hypersomnia and theorized as possible contributors to its pathophysiology including:

• Dysfunction of the GABAergic system
• Autonomic system dysfunction
• Altered functional or regional connectivity in the brain
• Circadian system dysfunction
• Dysfunction of energy metabolism

This episode is produced by Sleep Review and is episode 5 of a 5-part series sponsored by Jazz Pharmaceuticals. Visit Jazzpharma.com and SleepCountsHCP.com for more information. In episode 5, listen as Sleep Review’s Sree Roy and neurologist-sleep specialist Isabelle Arnulf, MD, PhD, discuss:

• Science doesn’t fully understand the pathophysiology of idiopathic hypersomnia. Research has revealed potential clues, however. For example, idiopathic hypersomnia is associated with changes in sleep staging and architecture. What does emerging science suggest are differences in nighttime sleep?
• How might the arousal index differ in idiopathic hypersomnia versus in people without it, and why might that matter?
• In addition to nighttime sleep dysfunction, other physiological changes have been observed in some patients with idiopathic hypersomnia and theorized as possible contributors to its pathophysiology. What is the GABAergic system and its possible role?
• What are some emerging findings surrounding idiopathic hypersomnia and autonomic system dysfunction?
• What is the evidence that supports the idea of altered functional or regional connectivity in the brain in people with idiopathic hypersomnia?
• There were fascinating studies done on skin fibroblasts, suggesting that circadian period length may be different in people with idiopathic hypersomnia versus in people without it. What role might circadian rhythm dysfunction have in idiopathic hypersomnia?
• What has science discovered about the possible role of dysfunction of energy metabolism in idiopathic hypersomnia?
• What further research would you like to see conducted on the pathophysiology of idiopathic hypersomnia?

Listen to Episode 1: Symptoms of Idiopathic Hypersomnia

Listen to Episode 2: Diagnosis of Idiopathic Hypersomnia

Listen to Episode 3: Differential Diagnosis of Idiopathic Hypersomnia

Listen to Episode 4: Burden of Idiopathic Hypersomnia