Well, the simple solution is stop bumping your noggins.
But in all seriousness, I chatted with some friends (a couple from NASA) about this as I have the same conserns, (as being new to the Sly look does raise questions) and asked them about this scenario. All came up with the same thing.
- If you hit your head, the level of pain is the same whether you have hair or not
- Hair is not the magical "Helmet" as it may seem to be. The level of hurt and injury is the same.
- Bald people with a head injury have an advantage over those with hair, as they can be assessed easier with the extent of the wound and emergency crews can take action quicker. Heck, they'd shave it off anyways. Save them the trouble!
If you can tell me any disadvantage, let me know.