The investigators wish to prospectively determine the response to CPAP in patients presenting with mild OSA. In many healthcare systems, patients with mild OSA (AHI 5-15) are not reimbursed for treatment. Although some evidence exists of the benefits of treating mild OSA when scoring as per AASM 2007 criteria, more evidence is needed. The investigators wish to add to this pool of knowledge and also increase the inclusion criteria to include the AASM 2012 definition of mild OSA. By including the 2012 AASM definition of mild OSA, the investigators will add novel information to the field by assessing the benefits of treatment in both sub-groups of mild OSA.