Rare diseases · Sign or symptom
Excessive daytime somnolence
Excessive daytime sleepiness
HP:0001262
What it means
A state of abnormally strong desire for sleep during the daytime.
This term refers to excessive sleepiness or feeling of sleepiness, or difficulty staying awake despite having had adequate sleep.
Rare diseases that can present with this55
Very common80–99%
10Common30–79%
17- Acute disseminated encephalomyelitis
- Angiostrongyliasis
- Arginine vasopressin deficiency
- Beta-ketothiolase deficiency
- Congenital hypothyroidism due to maternal intake of antithyroid drugs
- Congenital hypothyroidism due to transplacental passage of TSH-binding inhibitory antibodies
- Craniopharyngioma
- Gamma-aminobutyric acid transaminase deficiency
- Hemorrhagic fever-renal syndrome
- Inherited Creutzfeldt-Jakob disease
- Non-24-hour sleep-wake syndrome
- Non-progressive predominantly posterior cavitating leukoencephalopathy with peripheral neuropathy
- Ogden syndrome
- Postpoliomyelitis syndrome
- PURA-related severe neonatal hypotonia-seizures-encephalopathy syndrome
- Smith-Lemli-Opitz syndrome
- Steinert myotonic dystrophy
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: More than typical sleepiness during day
Tracking symptoms like this for someone? Eleplan keeps symptoms, diagnoses, medications and every specialist in one plan.
Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.