The key is that there is NO duty to retreat in your home as there is in public (as long as you're not the initial aggressor, and even then it's not cut and dry). There is no day time/night time distinction. An intruder can harm you or your family just as easily in the day as he/she can at night and that's why the law is written as it is. This comes from the "A man's home is his castle" school of thought, and one I completely agree with. If you're in someone's home without permission they can and should reasonably believe you are there to do them or their family harm. I heard that directly from the mouth of a former assistant county DA who currently works for the NYS Attorney General's Office Criminal Division, who has been involved with many deadly force cases in NY over the years (LE and non-LE). A State Police inspector who was present at the time agreed with the above.
I don't remember how clear this was made in my pistol permit course, but I think they pretty much skirted the issue if I remember correctly. I hate to say it but my course was taught by people who didn't know their asses from their elbows, on several topics. I think they basically said that "guns were for hunting only and if someone tries to kill you or your family, put down your useless AR-15/Glock/shotgun, call 911 and hope the perp is in a good mood", or some crap to that effect. I remember them specifically saying guns are no good for defense. Great bunch to teach new pistol owners, eh?