First of all, that has nothing to do with the point I made in my last comment; which is you can't dismiss peer-reviewed research based on personal experience.
Second, that is not how it works. There are varying levels of sleep. Some better than others. When your body doesn't need to go through rem sleep anymore it is sufficiently rested but that doesn't mean you feel like a ray of sunshine and immediately jump out of bed. There are other factors which make a person want to stay in bed longer than they should which leads to shitty non-rem sleep. Too much of this makes you feel groggy.
Second, that is not how it works. There are varying levels of sleep. Some better than others. When your body doesn't need to go through rem sleep anymore it is sufficiently rested but that doesn't mean you feel like a ray of sunshine and immediately jump out of bed. There are other factors which make a person want to stay in bed longer than they should which leads to shitty non-rem sleep. Too much of this makes you feel groggy.