Yes. When the sun doesn't
hit the room your circadian cycle is affected.
I used to close down the blinds and some times I'd wake up at 11 or 13 AM thinking that it's 9 AM.
Now, out of pure lack I live in a house which has no blinds. So I wake up alone no matter what, at 8:00 AM. If I need more sleep, due to late night activity, I get another one-two hours in the evening.
My parents were telling me and they were right. We need to make sure the sun can enter the bedroom in the morning.
To enhance sleep are necessary a couple of other things:
* Clean oxygen in the room (usually opening the windows 5 minutes before waiting for sleep will do)
* Proper room temperature (you need to feel warm UNDER the blankets, but not sweat)
* Less possible rumors in the room
* Avoid any CNS stimulant (coffee, black tea, coca-cola, etc.). A glass of red wine (just one) is very good. It's the recommended daily dosage (tannins) and although contains sugars, can act as a natural CNS inhibitor.
* light dinner, possibly 4 hours before (say you go to 00:15 AM to bed, it's good to have a light, rich in fibers dinner at 8-9 AM: Yogurt, Vegetables etc. Avoid fruits, after 6 AM, only black bread and vegetables should be taken).
* Close the screens and get a book if you don't feel really sleepy. This habit helps the circadian cycle in my personal experience. Watching movies/tv-series while waiting for sleep is an oxymoron: Your adrenaline levels, instead of getting lowered they get get higher, enhancing the opposite effect (alertness).
Of course, the BEST sleep, comes after a physically intense day and if you don't have physically intense days it's good to do some exercise in order to make your body feel tired at the time you need it to be tired.
PS. Wish you (and me) all the best, because it's one thing knowing (I study pharmacy, so I get a lot of this stuff) and a different thing doing... So this comment was a form of self-advice basically :-)