That midafternoon ennui that takes over most days isn't a sign that you are lazy or unmotivated; it just proves that you are normal. According to research, most people in creative or professional jobs can only churn out about six (worthy) hours worth of quality work a day; the rest is what it feels like — dithering.

Now at what point you end up spacing out — no matter how much you try to focus — depends on your chronotype; so whatever your optimal awake times are depends largely on biology. But according to neuroscientist Kenneth Wright, who told the New Yorker, "Cognition is best several hours prior to habitual sleep time, and worst near habitual wake time." That advice stands no matter your wake-up or sleep time, so you can best determine it for yourself, taking into account your natural cycles. For most of us in the middle of the bell curve of sleep cycles, the best productive and creative times to work are late morning and late afternoon. But no matter the time, it's only about six hours a day that we're really good for that truly useful, productive work.

Proof is in the pudding

A digital agency in Germany took it a step further and experimented with a 5-hour workday. Rheingans Digital Enabler said the new schedule was so successful that it kept the 25-hour work week. Lasse Rheingans told Business Insider that there was nothing to gain by working longer days except overexertion and exhaustion. Employees work from 8a.m. to 1p.m. with no overtime or weekend work. Of course if there's an emergency situation, Rheingans said employees will stay past 1p.m. but usually there isn't an emergency.

"We need fewer and fewer people, be it in trade, medicine or production. But the people you do need have to be creative, motivated, well-rested, satisfied and they have to be damn good," said Rheingans. "You need more and more at the peak of their cognitive performance. And you can't ask that of someone you're keeping in an office over eight hours. You don't need an eight-hour day in a society like ours anymore."

Flexibility for freelancers

However for people who don't work in a traditional office setting, those hours can be spread out over time, which is why it makes sense for more and more people to create their own hours: in essence, to work when we are most productive, and to do other things (errands, food prep, exercise) when we are not. That's what I do.

As an independent knowledge worker, I long ago found this to be true. (it is one of the reasons I went freelance; during my 20s I had too many jobs where I was expected to sit at a desk, determined by someone else's timeline.) I've noticed, as I've spent a couple solid years working at my own schedule, that I'm best from 9:30-11:30a.m., then from 2:30-5:30, then again from 9-11 (my chronotype is somewhat of a night owl). This self-knowledge has benefited me greatly; I pretty much don't work when I'm not productive anymore. I exercise midday, have a long dinner and relaxing time with my partner around 6, and read in the mornings.

If working for just six hours a day seems like a pipe dream, it wasn't always so: A hundred years ago noted economist John Maynard Keynes suggested that by 2030 we would all be working 15-hour work weeks. Obviously that hasn't happened, as we have all gotten mired in the restrictive idea of the eight-hour workday, and in fact, it may be hurting both our productivity and our personal lives.

But what if more of us were able to create our own schedules, making plans for the day that worked for our chronotypes, or lifestyles (incorporating best workout times, or best times to be with kids)? The answer is that we would all end up working fewer hours, which is healthier for us, and more productive for the companies we work for. Not to mention that we'd be happier overall, working when we are best able to work, and not spending hours 'pretending' to work. (Come on, who's not guilty of wasting time at work, just because you "have to" show up at your job, or you're "not supposed" to leave yet?)

Editor's note: This article has been updated since it was originally published in December 2013.

Starre Vartan ( @ecochickie ) covers conscious consumption, health and science as she travels the world exploring new cultures and ideas.

Why we should ditch the 9-5 workday
For knowledge workers, it's just plain unproductive to try to work 8 hours at a stretch.