One of the perks of being a freelance contractor is I can set my own hours. I virtually never just work 9-5. I work in concentrated chunks throughout the day with long breaks, sometimes an hour+ in length, in between. I often walk a lot and do stuff outside during the day, and then work quite a bit instead in the late evenings. Think about it: if all you're doing is staring at a computer screen and typing for your job, why on earth would you waste daylight hours doing that, and then when you're free it's night time? Huh?!
Everyone just pretends working after lunch. Then productivity goes up, but it’s end of workday. Not to mention all the random interruptions when someone is in the productivity zone.
Office work is utterly broken for brain intensive work.
As an anecdote, I tried to schedule interviews just after lunch break when I hoped interviewers are sleepy and they might get less ideas to ask questions. :)
The other preffered hour was right before the work day ends.