This can depend on various reasons. For me, for example, this happens due to the fact that, when I wake up, I do not see enough light, and the body thinks that it is still night and getting up early - I still need to sleep. But the main reason is the low temperature in the room, which is why you don't want to leave the cozy bed and crawl out from under the blanket :), + also the weather is often rainy and cloudy, this affects the lack of desire to go out and do anything at all
This is due to the work of our biological clock. They are tuned to sunlight, which becomes scarce in autumn. Light suppresses melatonin and makes us wake up. Our distant ancestors came from Africa, but in the middle zone, where we live, the climate is completely different, there is not enough sun, and the brain's habits have remained the same.
Special lamps can help, but their production, unfortunately, is still not established, they are quite expensive and are available only in special institutions where treatment is carried out. Twenty minutes spent in front of such a lamp with closed eyes is quite enough to get the necessary dose of light and wake up in a good mood. But until they are commercially produced, coffee and strong tea have to be dispensed with.
I think it's about atmospheric pressure. Autumn is the time of rains, when it rains, atmospheric pressure decreases, and when pressure is low, a person falls asleep faster and sleeps deeper.
If you have goals in life, plans for the year, a favorite thing for every day, then waking up is always easy and pleasant, regardless of the time of day and time of year.
My alarm is set at 5.45 six days a week. But usually I do not wait for him and easily get up 3-5 minutes before the signal.