Residual daytime sleepiness in patients with obstructive sleep apnoea syndrome: A service review in a tertiary sleep centre

Obstructive Sleep Apnoea Hypopnoea Syndrome (OSAHS) is frequently associated with excessive daytime sleepiness (EDS). There are sparse data on patients with OSAHS who are well treated with continuous positive airway pressures (CPAP) but continue to experience residual EDS. We sought to prospectively review a patient cohort to understand causes associated with this symptom. Patients with OSA and documented evidence of CPAP usage and respiratory control were recruited from a large tertiary referral centre (GSTT/2024/16137). Data are presented as mean (standard deviation). Data were collected between 05/2024 and 01/2025. Out of 63 patients that were identified and pre-screened, we included 50 (age 56.7 (13.1) years, gender (male: female) 33:17, body mass index, BMI 36.6 (9.5) kg/m2). Patients had been diagnosed with OSAHS (AHI 36.7 (20.0) events x hour− 1; residual AHI on CPAP 4.2 (3.8) events x hour− 1; p < 0.0001), were adherent to CPAP (6.2 (1.6) hours x night− 1), and remained sleepy (pre-therapeutic ESS 17.6 (3.7) points; residual ESS on therapy 14.9 (4.0) points; p < 0.0001). Common comorbidities included chronic pain (46%), Restless Legs Syndrome/Periodic Limb Movement Disorder (34%), mental health issues (anxiety/depression, 68%), other sleep disorders (36%), cardiovascular disease (68%), and type-2 diabetes (32%). Co-medication included analgesia (22%), antidepressants (58%), dopaminergic drugs (10%); antihypertensives (56%), antidiabetics (22%), no patient was taking benzodiazepines. The identified cohort of patients with OSA and residual EDS still experienced a significant improvement of their symptoms with CPAP therapy. However, residual EDS may be attributable to substantial comorbidities with sleep fragmentation and co-medication.