This is just a personal feeling. My biological clock has been off for the past few years.
I have never truly felt fully awake at work. I sleep in on the weekend (or when I am unemployed) and I don't feel fully rested until 10 am at the earliest. And it does affect my performance when I have a job and I am just another person dependent on coffee.
I might have a sleeping disorder. I was diagnosed with thyroid cancer this year (which has been hidden for years) and that can affect your quality of sleep. I may or may not also have narcolepsy. I have a snoring problem, but not to a point of obstructive sleep apnea. Unfortunately, I cannot afford to see any other specialist at this time due to being unemployed and the high copays.