Beating fatigue while drawing

Sometimes when I'm sitting  down & drawing, I keep feeling sleepy.

How do I beat fatigue while drawing?

not really sure....energy drinks maybe.....or a exercise routine that will overtime give you more energy....I get tired while drawing because of work and it annoys the crap out of me because I really don't do much at work lol :(

Maybe you can try standing at an easel if you have one. If you don't have one then you can take short breaks to get up and stretch or do some jumping jacks to get your blood flowing again!