Another defense against sleepiness is to break up your formal meditation into three fifteen minute sessions that are easy for your body to tolerate. Sit quietly for fifteen minutes, then stand for two minutes, then sit for another fifteen minutes, then stand for two minutes, then sit for a final fifteen minute session. This forty nine minute technique can be done once, twice, or three times a day for intense practice. You can use a meditation timer to let you known when to stand up, sit down, and begin and end meditation sessions.
The sit-stand method largely eliminates the problem of cramps, soreness, and numbness in legs often experienced by students attempting to sit for longer periods of time than the body was naturally made to sit. The standing breaks increase blood circulation which helps wakefulness. Comfort is maintained and we avoid the light sleep state hypnosis problem mentioned earlier.
The transitions between sitting and standing in this method are an opportunity to practice meditation in action. Normally, unless we are physically ill, our waking lives are spent in motion and activity. Meditation must not be thought of as something that is only done in a physically rigid state, far removed from the world of work and play. The goal is to become meditative continuously so that your very being becomes cosmically conscious permanently and irrevocably. When you stand up and sit down during meditation sessions, feel the inner flow (Chi) of meditation continue. Observe that your body is moving, watch your breath, but your basic existential identity remains the same.