I might suggest that seasonal change in sleep-requirements is enough to add 2 hours; or take 2 hours away. Don't get too excited, and also - start sleep tracking; easiest way to find out if you really do need less sleep.

I use a Basis watch to observe my sleep cycles and a fitbit to track total sleep (and the two of them in case of failure). There are apps that also track but I find they don't work with my pre-bed lifestyle (be awake in bed till I fall asleep, usually on my phone); and remembering to set the app was causing it to not work for me. (I also tried a zeo and I managed to take it off during the night)

The 3rd thing I would say is - trust your body. try to optimise for a lifestyle that does not need alarms; and trust your body to wake up when you are rested. still sleepy? go back to sleep.

I can send you a graph of my sleep/time if you are interested.