The gene that controls the circadian clock of our body may also be responsible for drug addiction.
The gene, also called the Clock gene apart from regulating our sleep and wake patterns also regulates a number of things like hormone levels, blood pressure, heart functions, body temperature, and currently established addiction to drug intake.
The gene regulates the inherent vulnerability to drug addiction by rewarding the experience related to drugs which are commonly used for abuse, like cocaine etc. the gene increases the reward response to cocaine through its effect on dopamine pathways. Dopamine is the neurotransmitter connected with the pleasure sensations of the brain.
The researchers who had drawn animal parallels had reported that mice deficient in the Clock gene had produced more dopamine when injected with cocaine, much more than the control mice that had the Clock gene. The first group also had more problems with their circadian rhythms when under the influence of cocaine; they were hyperactive with less sleep and exhibited a distinct preference for the location where the drug was administered.
The research suggesting the link between lack of sleep and tendency to abuse drugs may open new ways to research for the deeper understanding of human drug addiction.
Reference: Proceedings of the National Academy of Sciences, online edition, June 2005