Tarin has given some pretty solid advice. I would venture to say that most of us have had to deal with the "sloth and torpor" hindrance at one time or another in our practice. So, you're not alone.
That said, I am a particular advocate of the third suggestion on tarin's list. This is what the Buddha suggests in many a discourse:
"Here a bhikkhu, gone to the forest or to the root of a tree or to an empty hut, sits down; having folded his legs crosswise, set his body erect,
and established mindfulness in front of him, ever mindful he breathes in, mindful he breathes out." (MN 10; Satipatthana Sutta) This entails ratcheting up
viriya or energy and alertness, as in the examples in tarin's suggestion re: "listening for the whistle before a race" or "hearing an animal move nearby."
Also the seventh suggestion re: obtaining enough rest in general. One thing I found helpful was to give into the tendency for sleep and to take a brief nap before taking up the meditation session again. If you allow the body to obtain what it is seeking, you feel invigorated when taking up the meditation on the second try, and often the sleepiness tends to vanish. Combine that with the establishment of mindfulness, and you've got yourself a winning combination.
Best of luck to you.
tarin greco:
both your focus being too tight or too loose can cause drowsiness, as can being very mentally busy or turmoiled right before practice (when wakefulness then goes into a sort of shock when it meets the monkey mind), as can not getting enough rest in general, as can being particularly prone to sleepiness in general.
some suggestions:
- do walking meditation before sitting (never mind that novices rarely get any noticeable effect from walking meditation - just do it whole-heartedly and then go sit).
- establish clear mindfulness well before sitting down (for maybe 5 or 10 minutes). do it with the kind of intent alertness that you would have while listening for the whistle at the start of a race, or that you would have if you heard an animal move nearby in the woods. walking meditation can serve this purpose very well for some.
- sit with your eyes open.
- stand instead.
- pay attention to whatever sensations of light or lightness are present (there may be some round about your eyes).
- make sure you're getting enough rest in general.