Which among the following is increased during sleep induction ?

Stimulation cholinergic neurons in pontine reticular formation is responsible for sleep induction. When the activity of norepinephrine and serotonin containing neurons in locus coeruleus and raphe nuclei is increased, the activity of ACH-containing neurons in the pontine reticular formation decreases, leading to wakefulness. The reverse of this pattern leads to REM sleep. An even balance in the activity of these groups of neurons is associated with NREM sleep