If you often fall asleep during important meetings, you may want to blame your neurons in a brain area associated with reward and motivation, according to a recent study.
The University of Tsukuba and Fudan University researchers found that this part of the brain is the nucleus accumbens that can also produce sleep.
They used chemo-genetic and optical techniques to remotely control the activities of nucleus accumbens neurons and the behaviours they mediate.
They discovered that nucleus accumbens neurons have an extremely strong ability to induce sleep that is indistinguishable from the major component of natural sleep, known as slow-wave sleep, as it is characterised by slow and high-voltage brain waves.
Lead author Yo Oishi said that the classic somnogen adenosine is a strong candidate for evoking the sleep effect in the nucleus accumbens.
Adenosine has long been known to represent a state of relative energy deficiency and to induce sleep via adenosine receptors.
A specific subtype of adenosine receptors, the A2A receptors, are densely expressed in the nucleus accumbens.
Caffeine, the most widely consumed psychostimulant in the world, produces its arousal effect also in the nucleus accumbens by blocking A2A receptors.
The compounds that activate A2A receptors in the nucleus accumbens may open safe therapeutic avenues for treating insomnia, which is one of the most common sleep problems with an estimated prevalence of 10-15 percent in the general population and 30-60 percent in the older population.
The research is published in the journal Nature Communications.