Adenosine likely causes the 'feeling sleepy' side of microsleeps, while dopamine likely reduces microsleep events by promoting wakefulness. It has been shown that microsleeps correlate with spontaneous pontine-geniculate-occipital (PGO waves) waves, which suppress visual processing in the basal ganglia. When this pathway is not activated, cells in the superior colliculus (which causes release of dopamine) cannot be dis-inhibited via the basal ganglia, leading to poor processing ability and microsleep onset.[19]