Unintentional sleeping in has nothing to do with how tired you actually are. It’s because your body is clairvoyant and knows that the upcoming day is going to be difficult. As a result, it attempts to protect you by trying to force you to stay in bed.
Unfortunately, 73% percent of the time, the difficulty of the day is the result of a general lack of punctuality. So by keeping you asleep longer, your body actually guarantees the result that it’s trying to protect you from.