For me, the best way to induce sleepiness is to transmute, expanding my lungs to their full capacity in a relaxed manner, thereby taking in more oxygen to the blood and brain.

Breathing deeply during transmutation or mantralization are excellent for inducing relaxation, which leads to sleepiness.

To induce sleepiness takes practice. You also need to listen to your body and to practice when you feel the need to take a nap.

Just as we learn to crawl, walk, and use our body, so too learning to manage drowsiness with conscious attention is something that takes familiarization.

However, pranayama and transmutation can help you to relax to induce a sleepy state. I personally like to take hot salt baths (blessing the salt with its appropriate exorcism so as to absorb impurities from my internal bodies). This greatly aids in relaxing the body and inducing drowsiness suitable for meditation!

Just be careful not to doze off without being conscious (or to doze off in the tub)!