An hourglass mechanism keeping track of wakefulness and sleep (“sleep homeostasis”) and an endogenous oscillator with a period of approximately one day (lat. “circadian” = roughly one day) interact to regulate wakefulness and sleep. Our primary research is in the physiology and pharmacology of wake-sleep functions focusing on homeostatic sleep regulation in healthy volunteers and patients suffering from psychiatric and neurological disorders. We use a multidisciplinary, integrative approach combining state-of-the-art methods of pharmacogenetics, electroencephalography (EEG), brain imaging and neurocognitive testing to address open questions related to the physiological processes and neurochemical mechanisms regulating wakefulness and sleep in health and disease.