Multicenter randomized double blind study versus placebo during 12 weeks with at first, an escalating dose period followed by stable dose period at the selected dose.

This double-blind period can be followed by a 9 months open-label period if the patient wishes to continue with the study product.

The first period (12 weeks double blind period) will aim at demonstrating the efficacy and safety of BF2.649 by verifying whether the results of BF2.649 are superior to those of placebo.

The aim of the second period (open label extension phase) will be to assess the long-term tolerance, as well as the maintenance of the BF2.649 efficacy.

Inclusion Criteria:

• patients with OSA treated by nCPAP but still complaining with EDS
• ESS score > or = 12

Exclusion Criteria:

• patient suffering from insomnia without OSA
• co-existing narcolepsy
• patient with sleep debt not due to OSA
• acute or chronic severe disease