On a physical level, cannabis helps relax muscles and reduce spasms, including those caused by spinal injury or MS. Many adults also often use cannabis to relax and unwind after work, to let go of the day's tensions and to adjust their mental attitude. Most people prefer not to smoke when they have a lot of things to get done, because smoking cannabis (especially indica) can sometimes make one tired, sleepy or feeling sluggish. Other people become energized or even "hyper" when they consume cannabis. Other people find that it gives them a lift and change of perspective to keep them alert.

Excerpted from the Hash, Marijuana, Hemp Museum of Amsterdam
http://www.veryimportantpotheads.com/index.html
PO Box 2662, 1012 DV Amsterdam, The Netherlands