Abstract
This study shows that although strong evidence demonstrates that caffeine abuse is a common cause of sleep problems, this substance disorder is not being considered as a differential cause of poor sleeping habits and sleep disorders in the outpatient psychiatric setting. Caffeine has been shown to have various effects on sleep including the effects on polysomnographic sleep variables and effects on spectral electroencephalogram sleep variables. Caffeine also exerts its influence on sleep via interaction with adenosine receptors and acts as an adenosine receptor antagonist. Thus, we postulate that caffeine consumption may be an aetiology in many sleep-related complaints, and we suggest that when evaluating the history of substance abuse in a patient in the outpatient clinic, the history of caffeine consumption should be included in the psychiatric evaluation.