Does effexor (venlafaxine) effect rem sleep?

Yes: All the ssri antidepressants have an impact on rem sleep. Though Effexor (venlafaxine) is not technically an ssri, it is a dual action agent (snri) that has ssri activity in addition to norepinephrine reuptake inhibition. Most patients complain of increased dreaming, or more vivid dreaming, which suggests an impact on rem sleep, since dreaming occurs during rem sleep.