Does olanzapine make you sleepy, and gain weight?

Yes, olanzapine is well known to cause weight gain by slowng down glucose and lipid metabolism, its a very effective drug though.

Olanzapine is both very sedating and can cause extreme weight gain. I have been on the maximum dosage for it for about 2 years now. I gained 3 stone in weight from the drug but I was too skinny for my height so I welcomed the weight gain. I like the sleep it gives me as I used to suffer insomnia, I find after about an hour of taking it I fall into a very deep sleep.

i found olanzapine to be really good at controlling my manic episodes, but i had other side effects including disturbed sleep, bad itching of the skin on my neck and cleavage and large rapid gain of weight approximately 80 pounds. However i would not go off it as it has been the only thing that controls my mania.