To answer the question whether a previously detected breath profile in patients suffering from obstructive sleep apnoea (OSA) can be found in a cohort of patients with suspected OSA using mass spectrometry (validation study).

Inclusion Criteria:

• Clinical suspicion of obstructive sleep apnoea syndrome (based on clinical symptoms such as increased daytime sleepiness; Epworth Sleepiness Score (ESS) > 10).
• Age between 18 and 85 years at study entry.

Exclusion Criteria:

• None

Patients with clinical suspicion of OSA