Toprol-XL and seizure

My mother is on Toprol-XL, and she has complained of being so fatigued, she sleeps so much, and this is someone who has always had a tremendous amount of energy. The other thing, and I would love a reply to this - she said she's experienced something at night while sleeping that feels like a seizure. She describes this as follows, "like my brain is shaking or trembling inside my head and my hands are trembling too." Has anyone else experienced this? Please let me know.