On Treatment but Still Sleepy

Cause and Management of Residual Sleepiness in Obstructive Sleep Apnea

Sandrine H. Launois; Renaud Tamisier; Patrick Lévy; Jean-Louis Pépin


Curr Opin Pulm Med. 2013;19(6):601-608. 

In This Article

Characteristics of Patients With Residual Sleepiness

Severity of residual sleepiness is quite consistent across studies, with an average Epworth score on effective CPAP of 14/24,[17,26,29,30] which underscores the clinical relevance of the issue. Objective testing actually confirms the increased sleep propensity.[26] At the time of diagnosis, residual sleepiness patients exhibit more sleepiness than patients who respond to CPAP.[17,26]

Mean CPAP use is not shorter in residual sleepiness patients than in nonsleepy patients,[26,28–30] except in one study in which residual sleepiness patients used CPAP 10.6% less than patients without residual sleepiness,[17] but residual sleepiness prevalence consistently decreases with longer CPAP nightly usage, as mentioned above[17,26,28–30] (Fig. 1). When evaluated systematically, CPAP side-effects are more common in patients with residual sleepiness than in CPAP responders.[17]

Patients with residual sleepiness display baseline and post-CPAP characteristics that distinguish them from patients who do respond to CPAP.[17,26,28–30] Interestingly, they are not more obese and only in one study were they found to have comorbid conditions such as chronic obstructive pulmonary disease, cardiovascular disease, diabetes and depression.[28] There is no consistent pattern for age or sex, although residual sleepiness patients tend to be younger at the time of diagnosis.[17,30] They have less severe OSA at baseline, whether severity is assessed by AHI, oxyhemoglobin desaturation index or lowest SaO2.[17,26,28–30]

Only one study has examined sleep parameters in residual sleepiness patients.[26] In two carefully phenotyped groups of OSA patients with and without residual sleepiness compared with healthy controls, overnight PSG showed decreased sleep latency and decreased amount of slow wave sleep in residual sleepiness patients. They also had more daytime sleep. In spite of a greater PLM index, they had fewer arousals than OSA patients without residual sleepiness.

When evaluated after several months of CPAP treatment, residual sleepiness patients complain significantly more than CPAP responders of fatigue, depressive symptoms, unrefreshing sleep and impairment in energy and quality of life.[17,26,30] At baseline, they already have remarkably worse overall health self-perception, fatigue, and depressive symptoms.[17] Clearly, in residual sleepiness patients, residual symptoms are not limited to sleepiness, but also include fatigue, poor health self-perception, depressive symptoms, and so on, suggesting the existence of a true 'CPAP-resistant syndrome'. Indeed, a marked proportion of patients do not normalize neurobehavioral performances despite optimal CPAP treatment.[14,26] Interestingly, when a stimulant drug is used to alleviate sleepiness, other associated symptoms such as fatigue and activity level scores improve as well[31–38] (see below and Table 1 ).