Sheila's state of health was nothing that couldn't have been resolved. She'd have been in a state of utter confusion about " what was wrong with her , why did Colin choose to leave her,why has Colin got her children,why is her mother so mean to her ". Her mind would have been in turmoil and she was reaching out for the help that didn't come. What a dreadful state to have been in for anyone.
Then she was given medication to knock her out,which she didn't want or need until she'd asked for it to be reduced,so she was fully aware that she hadn't liked or tolerated the drowsy effect that it was giving her. Had it been oral,she wouldn't have taken it at all. Other medications weren't taken because of their effects.