Days don't start at 11pm
Why do you start my days at 11pm. Lost my streak at 11:00pm. Why not at midnight?
What time zone were you in when you originally created this account? That is the time zone it should continue to be in. I am careful on Sunday in the afternoon the new week starts, which should not affect the day streak, but I don't take a chance. Also the last and first day of the month and year are days that I don't take a chance with. I definitely do my practice in the morning on those days. http://duolingo.wikia.com/wiki/Streak
You may be interested in the DuoTweak userscript. http://duolingo.wikia.com/wiki/Duolingo_Userscripts
That is incorrect because I am in the UK and my day is midnight to midnight GMT.
I believe that your own timezone is set to what it was when you first registered with Duo. You can see where Duo thinks you are by going to www.duolingo.com/users/your_username where you will see a lot of HTML like code. If you use your browser to search for timezone, you will see which timezone Duo thinks you are in.i
Same issue as pkh97; Duolingo thinks I'm on the East Coast of the U.S., but I've lived in California my whole life. I've looked around for a place to change my timezone but haven't seen one anywhere, and I don't recall seeing an option to set or change it when I registered.
At least your day starts close to the real deadline. Mine is at 5 p.m. I think it's Indonesian time and I live in Europe. I emailed support about it and got no answer. I also read a lot of similar threads and they all seem to come to the same conclusion. Basically, you can't do anything about it. But if you use android apps, your time zone might change based on your location. So if you go traveling, your time zone might change.