Seven Antidotes to Drowsiness:
1. Change one’s attitude and make meditation more dynamic.
2. Reflect on inspiring passages of the Dhamma.
3. Recite passages aloud.
4. Physical stimulation, including rubbing the ears.
5. Washing one’s face.
6. Looking at a light.
7. Brisk walking meditation.
(from Anguttara Nikaya 7.58)