A review of the different publications dealing with melatonin in humans shows that this field has been very active in the last few years. Normative melatonin values have been defined. Various relationships between melatonin and other traits have been studied, such as sleep, circadian rhythm, surgical stress and anaesthesia. Age-related melatonin studies and melatonin during depression and other...

Positron emission tomography (PET) is an imaging modality that gives information on tissue metabolism and functionalism, different from other imaging techniques like computed tomography (CT) and magnetic resonance imaging (MRI), which provide anatomical or structural information. PET has reached its development in biomedical research because of its capacity to use analogous compounds of many en...