**G47.00 — Insomnia, unspecified** is used when difficulty initiating or maintaining sleep is documented but no more specific subtype (F51.0 nonorganic, G47.01 medical condition-related, G47.09 other) is identified.
Insomnia is one of the most common reasons for primary-care visits worldwide. Persistent insomnia (≥3 nights/week for ≥3 months) typically warrants further evaluation.
Belongs to **Chapter G** — Diseases of the nervous system.
