I think these types of studies are all going to be fatally flawed with a bunch of very-hard-to-untangle factors: since &quot;40 hours&quot; (or more) is the &quot;expected norm&quot; then if you&#x27;re working less you&#x27;ve either fought incredibly hard to do so (which I personally have), you have way more freedom to choose working hours than most people or you&#x27;re &quot;forced&quot; to work less (or more) for some reason.<p>e.g. my first thought about the &quot;increased hypertension in workers reporting &lt; 7 hours&quot; (a paper I haven&#x27;t read, mind) is that they&#x27;re stressed about finances because they&#x27;re working part-time (or the &quot;hours&quot; was averaged over the year or something, and they spent some time without a job).<p>Now, if you&#x27;ve <i>chosen</i> to work many more hours then it seems intuitively obvious that you&#x27;ll be more productive. There&#x27;s also the hard-to-study factor of <i>what</i> you&#x27;re working on. For example, many free-software developers are doing their free-software-developing in their &quot;non-work&quot; hours -- so they might be &quot;working&quot; (in the sense of producing code) 80+ hours a week, but will likely only get &quot;counted&quot; as whatever their day job was. (If there <i>are</i> studies that account for &quot;what you do with your other time&quot; against productivity, I&#x27;d be very keen to read them).<p>In a similar vein -- and as John said in the original post -- if you&#x27;re &quot;stuck&quot; on something (e.g. can&#x27;t do any more &quot;design the hard algorithm&quot; thinking) and switch to something &quot;boring&quot; that still needs to be done (e.g. make the Makefile suck less) that&#x27;s still &quot;more productive&quot;. But, as others have pointed out, many developers <i>don&#x27;t</i> have that freedom -- they <i>have</i> to keep pounding their face against whatever bug they got assigned. And if you&#x27;re stuck, but have to keep working on it, I&#x27;d bet a lot that your productivity goes to shit.<p>So, all that said, I personally believe (note: not scientific! ;) that we&#x27;d be far better off to have shorter expected&#x2F;forced &quot;working weeks&quot;. And I don&#x27;t mean that <i>everyone</i> should be forced to work less! This may (or may not!) have a &quot;productivity&quot; impact for employers but if you looked at individuals&#x27; &quot;productivity&quot; (including work and &quot;non-work&quot; parts) I think it would go way up -- precisely because this would give the vast majority of people way more <i>choice</i> about what they get to work on. This -- I completely unscientifically presume -- would also have a large positive effect on people&#x27;s reported happiness.<p>That is, they&#x27;d be spending less time smashing their face on that bug at work and get more time to do whatever else they like to do -- free-software, painting, writing, building things, etc.<p>In any case, I know that for me personally being <i>forced</i> to work 40+ hours a week on the same thing is completely toxic to my creativity and productivity at programming and I&#x27;ve worked very hard to get paid less (to work less). I can also tell you that nearly every co-worker or friend I&#x27;ve told of my myriad different arrangements to achieve this have wanted to do the same (but feel they &quot;can&#x27;t&quot;). The only exception seems to be when people realize the bit about &quot;paid less&quot; ;) and can&#x27;t do (or don&#x27;t want) that. Interestingly, I still have spent a bunch of my increased leisure time writing software -- but for myself, or free-software instead of &quot;for work&quot;. Of course, I&#x27;ve also spent a bunch of it doing things for pure enjoyment.<p>Now, of course, that&#x27;s all just anecdotal. But, for me, less &quot;must work on X for $&quot; time means a lot more happiness and a lot more &quot;productivity&quot; (if you look at everything I do with my time).