I personally find that I work much better at night, when there are far fewer distractions - less emails, notifications on my phone, tel calls, posts on forums even.
I also think ‘the sleepy brain’ may something to do with it too (where basically, at a level of tiredness you can’t multi-task as easily, meaning you are forced to focus on one thing) - these articles cover it well:
It is quiet at night after everyone else goes to bed! Plus, considering that I am NOT a morning person, nighttime is when I get to read, catch-up, play with new stuff, etc.
I am consider a morning person, so I like to spend my time working and doing before night coming. I often few tired and low energy, and I do something really dummy to relax the rest of the day. Likewise, I deactivated almost my notification in desktop and mobile to avoid killed my focus time.