Have you ever woken up after a long night’s sleep only to feel exhausted and confused? You might not just be tired — experts say you could be suffering from a rare condition known as idiopathic hypersomnia (IH), which leaves people feeling persistently sleepy despite getting plenty of rest.

Idiopathic hypersomnia is a neurological sleep disorder that causes excessive daytime sleepiness. People with this condition often sleep for long hours, yet still wake up feeling groggy and disoriented.

According to Hypersomnia UK, fewer than one in 25,000 people in the United Kingdom are affected by this disorder. However, the actual number may be much higher, as many cases go undiagnosed. This means thousands of individuals could be suffering from IH without even knowing it.

Symptoms often overlooked or misunderstood

Those living with idiopathic hypersomnia often find themselves in a constant state of fatigue. Even after sleeping well through the night, they struggle to stay awake during the day and may experience confusion upon waking.

Because the symptoms can resemble other sleep disorders or mental health conditions, many patients face delays in receiving a proper diagnosis. Previous studies have even suggested that idiopathic hypersomnia could be more common than conditions like epilepsy or bipolar disorder.

The exact cause of idiopathic hypersomnia remains unclear. Experts believe it is likely a neurological problem — meaning it originates within the brain’s control of sleep and wake cycles.

Currently, there is no known cure for the disorder. Treatments mainly focus on managing symptoms and helping patients maintain daily functioning, though research continues to uncover more about its underlying mechanisms.