Joel Spolsky writes about flow:
We all know that knowledge workers work best by getting into “flow”, also known as being “in the zone”, where they are fully concentrated on their work and fully tuned out of their environment. They lose track of time and produce great stuff through absolute concentration…trouble is that it’s so easy to get knocked out of the zone. Noise, phone calls, going out for lunch, having to drive 5 minutes to Starbucks for coffee, and interruptions by coworkers – especially interruptions by coworkers – all knock you out of the zone. If you take a 1 minute interruption by a coworker asking you a question, and this knocks out your concentration enough that it takes you half an hour to get productive again, your overall productivity is in serious trouble.
Jason Fried comments:
One tip to help you create some alone time is… Set up a rule at work: Make half the day alone time. From 10am-2pm, no one can talk to one another (except during lunch). Or make the first or the last half of the day the alone time period. Just make sure this period is contiguous in order to avoid productivity-killing interruptions.
Trying to get some work done on my dissertation, I have started waiting a couple of hours every morning before I start reading e-mails. This has already proven to be very efficient, and I will probably try and set aside more distraction-free time as I get closer to the deadline.