That sounds pretty bad. People need atleast 6 hours of uninterrupted sleep to be on top of their game. I would go to a sleep specialist MD (usually a pulmanologist or neurologist) maybe you have a RAM sleep disorder or obstructive apnea.
It can’t be bad if it is how we developed prior to artificial light. It was probably how we survived in the jungle. By having a few people wake up at points during the night, it probably helped keep predators away.