Different molecules (e.g. dopamine, opioids, orexins, serotonin) and brain circuits (limbic, arousal) have been implicated in the rewarding effects of natural and non-natural rewards. It is still unknown whether those molecules and circuits have a role in the entrainment of the SCN clock and other brain oscillators by reward cues. On the other hand, when stimulation by reward signals (e.g. psychostimulants) exceeds the physiological range, consequences in behavioural and physiological rhythms may occur. In addition, alterations in circadian rhythms may be correlated with the apparition of some mood psychiatric disorders.

Mutations of some clock genes alter the behavioural responses to drug intake, indicating that drug addiction may be regulated by the circadian system.

Thus, using molecular and behavioural approaches our principal aims are to determine:

1. The effects of natural (palatable foods) and non-natural rewards (addictive drugs) on the circadian system (SCN and other brain oscillators), and the central and peripheral (hormones) mechanisms modulating these effects.
2. Implication of circadian rhythms and clock genes in the regulation of compulsive/addicted behaviours to natural (palatable foods) and non-natural rewards (alcohol, cocaine, and methamphetamine), and the pathological mood states (depression).