Sleep SleepMTNR1BMTNR1B is a receptor for melatonin, one of the key sleep hormones. SleepGRIA3GRIA3 is a glutamate receptor important in neuronal signaling. SleepADORA2AADORA2A is a receptor for adenosine; adenosine binds and promotes the induction of sleep. SleepGAD1GAD1 is an enzyme which catalyzes the formation of the important neurotransmitter GABA. SleepADAADA is responsible for breaking down the sleep promoting adenosine, thus promoting wakefulness.