Your body makes cannabis when you run, no really

Remember this next time you're out for a run.

If you run, you know the feeling. As you're about to hit a wall and suddenly a bout of energy kicks in. While it's usually attributed to endorphins, they may actually be caused by endocannabinoids, self-produced chemicals similar to those found in marijuana.

A new study by researchers at the University of Heidelberg medical school in Germany found that mice showed elevated levels of both endorphins and endocannabinoids after running, an activity they engage in for fun.

Wired report 'the researchers also observed that mice were less sensitive to pain, less anxious and more tranquil after running, shown by their willingness to spend time in lighted areas of their cages rather than retreating to dark corners.'

Gives a new meaning to the term 'runner's high'.