The social aspect of khat chewing is as important, if not more important, than the physical high it creates. In Yemen, for example, khat sessions are a major part of life; participants regard the time spent chewing as productive time, such as when business deals are arranged, and communication is enhanced.

In Yemen, work days end between 2 P.M. and 3 P.M., at which time groups of 10–50 people convene in a home to dine and chew. In almost every house there is a mafraj, the most pleasant room in the house; it is in this room that khat sessions are held. No food is served with khat; only water is available to help wash the leaves' juices into the system. Between 3.5 and 7 oz (100 and 200 g) of leaves are chewed over three or four hours.

Stimulation can occur within the first 15 minutes of chewing...