“Why would you sedate a stroke patient?”

Some patients become restless and anxious, so sedation will calm them down.

Depends for what, if the patient is sedated to be still during MRI or interventional radiology procedure it is acceptable.

Sedation may be required for a number of different reasons: anxiety, to ease discomfort for an uncomfortable procedure, to prevent or minimize patient movement, etc. You have to remember there is varying depths of sedation. An extremely mild sedative may be the equivalent of having a few drinks of alcohol. Or, if the situation warrants, the sedation, can be so deep that a patient will only respond to a painful stimulus. The type and depth of anesthesia is determined by a number of factors: patient's physical and mental health status, procedure being performed, duration of procedure, pain produced by the procedure, etc.

It depends, perhaps for a procedure or if they were agitated. Tough to say without more information.