Last updated: August 15, 2026 · 7 min read Sleep is essential in both our physical and mental health, but for some individuals, it is not sufficient to have sound sleep. Think of sleeping ten hours at night and still being left feeling exhausted the following day. It is an actual scenario in people affected by Idiopathic Hypersomnia (IH). This uncommon yet debilitating sleep disorder is often neither understood nor diagnosed correctly.