Via David Allen, Red Herring reports that email is twice as damaging as marijuana for your mental acuity:
Scientists at London’s Institute of Psychiatry found that environments with distracting technologies lower IQ by an average of more than 10 points when compared with quiet conditions. By comparison, other research has shown that smoking marijuana causes just a 4-point drop. A 10-point reduction is similar to the impact of missing an entire night’s sleep.