Rare diseases · Sign or symptom
Drowsiness
Sleepy
HP:0002329
What it means
Abnormal feeling of sleepiness or difficulty staying awake.
Rare diseases that can present with this35
Very common80–99%
3Common30–79%
15- Acute liver failure
- Argininosuccinic aciduria
- Autosomal dominant hyperinsulinism due to Kir6.2 deficiency
- Autosomal dominant hyperinsulinism due to SUR1 deficiency
- Benign paroxysmal torticollis of infancy
- Citrullinemia type II
- Dopa-responsive dystonia due to sepiapterin reductase deficiency
- Ethylene glycol poisoning
- Homocystinuria without methylmalonic aciduria
- Hyperinsulinism due to HNF1A deficiency
- Hyperinsulinism due to UCP2 deficiency
- Infantile spasms-psychomotor retardation-progressive brain atrophy-basal ganglia disease syndrome
- Methylcobalamin deficiency type cblE
- Ornithine transcarbamylase deficiency
- Postencephalitic parkinsonism
Sometimes5–29%
17- 6-pyruvoyl-tetrahydropterin synthase deficiency
- Acquired methemoglobinemia
- Alpha-mannosidosis, adult form
- Alpha-mannosidosis, infantile form
- Crigler-Najjar syndrome
- Early-onset epilepsy-intellectual disability-brain anomalies syndrome
- Fructose-1,6-bisphosphatase deficiency
- Histiocytoid cardiomyopathy
and 9 more in this range
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: Abnormal drowsiness · Sleepiness · Somnolence
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.