I find Seroquel XR to be more sedating. Regular (instant release) Seroquel seems to wear off rather quickly, whereas the XR is a constant influx of sedation.

I am not a dr, but I would recommend the XR over the instant release if you're looking to stay asleep. Only problem is that you are kinda sedated throughout the day with the XR. However, I think it is better for controlling mania for that reason. You're also more calm.

I had to go off all forms of seroquel because it gave me the worst depression I have ever experienced in my life when the dose was increased to 250mg.

Fun Seroquel story:

My grandma had BP. She literally took seroquel instant release 3 times a day for agitation, but she STILL only slept 2-3 hours a night, if that. I wish the dr would have given her seroquel XR, but I drove her to IP before we could request that. (Her geriatric psychiatrist was an asshole anyways.) That's when IP drs tried trazadone, which made her bounce off the walls, gave her rapid speech, caused her to pace like crazy, become completely delusional 100% of the time, and made her start hallucinating. Then she started biting other patients, kicking them, hitting them with stuff, etc.. She literally threatened to kill them, too. And the problem was that although she was 82, she was in a geriatric IP wing and she was actually capable of RUNNING. She would literally bite someone who used a cane or walker and then run down the hall so they couldn't catch her!!

After that chaos, she was given zyprexa for 7 days, to no avail. Then they tried depakote to relax her and even out her mood, but it only agitated her. Geodon was the only thing that made her sleep.

Edit: I feel bad for this guy named John. He said something to her that wasn't nice, so she bit him every time she saw him. lol. She also pushed him on the ground though. And the dude was like 85.