Hello! Thank you for your question on HCM! I appreciate your concern. I think that feeling sleepy is normal after a head concussion. It is caused by a temporary dysfunction of the brain, and may be a sign of brain swelling. Nausea, headache and dizziness are common symptoms too after a head concussion. I agree with your doctors who are telling you not to sleep, because they are monitoring your conscience status. I would recommend you to have a little rest and do not worry about it. It will get better. If these symptoms get worse or you feel other symptoms like numbness etc, a bran CT scan would be necessary to exclude an intracranial hemorrhage. Hope to have been of help! Greetings! Dr. Aida