http://www.theguardian.com/education/2015/oct/24/want-to-learn-faster-stop-multitasking-and-start-daydreaming?CMP=fb_gu

Students
Use your head
Want to learn faster? Stop multitasking and start daydreaming
Neuroscientist Daniel Levitin explains how students can avoid letting social media and multitasking ruin their study time

Make time to let your mind wander
Healthy breaks can hit the reset button in your brain, restoring some of the glucose and other metabolic nutrients used up with deep thought. A healthy break is one in which you allow your brain to rest, to loosen its grip on your thoughts.

Activities that promote mind-wandering, such as reading literature, going for a walk, exercising, or listening to music, are hugely restorative. Many students find that a work-break cycle of 25 minutes work followed by five minutes rest, or even two hours of work followed by 15 minutes of rest promotes efficiency to the extent that they get back the time they spent resting, and then some. A 15 minute nap is even better.