You talk about the length of your sleep but have you considered variability of your sleep? For me sleeping always 7h30 seems to greatly increase my productivity in the long run. I sometimes add a few sleep cycle every few week ends but try to stick to a regular sleep schedule instead of thinking in terms of duration.
You might want to try by first waking up always at the same time, regardless of when you fell asleep.
You talk about the length of your sleep but have you considered variability of your sleep? For me sleeping always 7h30 seems to greatly increase my productivity in the long run. I sometimes add a few sleep cycle every few week ends but try to stick to a regular sleep schedule instead of thinking in terms of duration.
You might want to try by first waking up always at the same time, regardless of when you fell asleep.