F51.1Nonorganic hypersomnia
Code usage status
Primary diagnosis
May be used as the primary diagnosis
Apply only when it matches the confirmed diagnosis and the documented clinical record.
Specificity
Complete code in the classification
Use when the diagnosis matches and no exclusion applies.
- Chapter V
- Mental and behavioural disorders
- Official Vietnamese name
- Ngủ nhiều không thực tổn
- Additional WHO coding guidance
- Hypersomnia is defined as a condition of either excessive daytime sleepiness and sleep attacks (not accounted for by an inadequate amount of sleep) or prolonged transition to the fully aroused state upon awakening. In the absence of an organic factor for the occurrence of hypersomnia, this condition is usually associated with mental disorders. Excl.: hypersomnia (organic) (G47.1) narcolepsy (G47.4)
Related F51 codes
F51
Nonorganic sleep disorders
F51.0
Primary diagnosis candidate
Nonorganic insomnia
F51.2
Primary diagnosis candidate
Nonorganic disorder of the sleep-wake schedule
F51.3
Primary diagnosis candidate
Sleepwalking [somnambulism]
F51.4
Primary diagnosis candidate
Sleep terrors [night terrors]
F51.5
Primary diagnosis candidate
Nightmares
F51.8
Primary diagnosis candidate
Other nonorganic sleep disorders
F51.9
Primary diagnosis candidate
Nonorganic sleep disorder, unspecified
Clinical record checklist
View coding guide →- Confirm that the code matches the final documented diagnosis.
- Use one primary-diagnosis code and record only relevant additional conditions.
- Review Ministry indicators, inclusions, exclusions and notes.
- Do not infer a diagnosis beyond the clinical record.
2026 regulatory basis
Indicators are taken from columns 24–29 of the classification accompanying Circular 06/2026/TT-BYT, cross-referenced with Decision 1849/QĐ-BYT and Official Dispatch 4059/BYT-BH.
