It's normal for cats to sleep a lot after vaccination. Cats are prone to lethargy, loss of appetite, and drowsiness within two days after vaccination. If they haven't recovered after three days, it's best to take them to a veterinary hospital for a checkup. 
After a cat receives a vaccination, it needs extra nutrition, and you shouldn't bathe it immediately, otherwise it's prone to getting sick or catching a cold. Cats may experience mild vaccine reactions or stress after vaccination, and sleeping a lot is normal; they usually recover within 1 to 2 days. During this time, owners should keep the cat's environment quiet and take measures to keep it warm.
If the condition does not improve after two days, or if it worsens, it is recommended to consult a veterinarian immediately for medication. Do not bathe your cat before or after vaccination to prevent them from catching a cold.
