Cat sleepy after deworm

I gave my cat a deworm pill as instructed by the vet in the lunch time around 1pm a around 6pm my cat got very sleepy and she has been slepping for 2 hours. I called 2 24/7 vets and they said to monitor her and in case we feel worried to bring her to the vet. Has anyone experienced this symptom after deworming the cat? It is my first cat and I have never experienced it.

Edit: after 4h sleeping I brought corn for my wife she felt the smell and jumped from the bed to ask for corn. She looks fine now. I brought her cat food and water for her and she ate and drank it.