What should you know about obesity hypoventilation syndrome?

Breathing may become too shallow or slow to remove enough carbon dioxide, particularly during sleep. Oxygen can also fall. People may wake unrefreshed, develop morning headaches, feel unusually sleepy or struggle with activity. Loud snoring and witnessed pauses can point to obstructive sleep apnoea, but the two conditions are assessed separately.

Diagnosis usually involves a clinical history, examination and tests of oxygen, carbon dioxide and sleep breathing. Other causes of raised carbon dioxide, such as certain lung, muscle or medicine-related problems, may need to be considered.

Arrange medical assessment if you have persistent daytime sleepiness, morning headaches, breathlessness or disturbed sleep. A clinician may arrange blood tests, breathing tests or a sleep study. Treatment can include night-time positive-airway-pressure support, management of related conditions and a supervised weight-health plan.

Call emergency services for severe breathlessness, blue or grey lips, inability to stay awake, new confusion, collapse or chest pain. Do not drive if sleepiness is overwhelming or you have nodded off unintentionally. Worsening morning headaches or swelling should receive prompt medical review.

Ask whether your symptoms warrant a sleep study, how carbon dioxide will be checked, whether obstructive sleep apnoea is present, and how to use any breathing device safely.