There is an abundance of "medical advice" regarding all sorts of maladies, some helpful (chicken soup and garlic for a cold) and some not-so-helpful. One frequently provided piece of advice regarding concussions is that the patient shouldn't be allowed to sleep because they may fall into a coma. This is an old wives tale based on instances when a concussion has not been examined healthcare professional and an epidural hematoma (broken artery) has been undetected.
The most important thing to do if you’ve hit your head and may have a traumatic brain injury (aka, concussion) is to see a qualified medical professional. The risks from a traumatic brain injury can be fatally serious and a medical professional will test you for symptoms of epidural or subdural hematomas. If you experience loss of consciousness, have dilated pupils, headache, trouble walking or talking, vomiting or dizziness, a medical examination is essential. Even if you don’t have these symptoms, don’t say, “I’m fine” and ignore the event. Get checked. However, after you’ve been examined, get some sleep. The brain needs to rest and recoup.