  We previously developed a neurocomputational model called the
reward-attention circuit, which has been used to investigate the separate
effects of nicotine and alcohol on attention focus. The model is based on known
circuits linking midbrain dopaminergic neurons to the thalamocortical loop and
is sufficiently versatile to capture diverse phenomena. In this work, we used
the model to study the influence of both nicotine and alcohol on sleep latency
(time to fall asleep). In line with findings from other studies, our
simulations suggest that nicotine can have a stimulating effect that increases
sleep latency, promoting wakefulness, and, in contrast, alcohol can have a
sedating effect that induces sleep. Together, our results suggest insights into
alterations in mesothalamic dopamine activity and sleep. Also, they raise
speculations about aspects of insomnia and low mesothalamic dopamine.
