The position of your head in meditation is very important.
Your head should be balanced, and should almost seem to float effortlessly on top of your spine. You can imagine the crown of your head being drawn upwards, as if the string of a baloon were attached to it.
Your chin should be slightly tucked in, and the back of your neck should be long and relaxed. So as you tuck in your chin, feel the muscles on the back of your neck relaxing and lengthening.
If your chin is tucked in too far, so that your head hangs forward, then you’ll find either that you tend to feel dull and sleepy, or that you become caught up in circular, and often not very positive, loops of emotions.
If your head is tilted too far back, so that your chin is in the air, you’ll find that you tend to get very caught up in thinking, and that you become rather “speedy.”
But when your chin is nicely tucked in, you’re able to be aware of both your thoughts and emotions without getting lost in them.
Sometimes if I’m feeling dozy in meditation (the mid-afternoon sits on retreats can be killers) I actually raise my chin a little above the recommended level. I then make the position of my chin the main focus of the meditation practice. As I start to doze of and the chin starts to sink down, I draw it back up again.
If I don’t start with my chin raised the by the time the chin starts sinking from its normal position it’s generally too late to catch it and the next thing you know is that you have that uncomfortable feeling of jerking awake.
Many people wonder whether the eyes should be open or closed during meditation, and different Buddhist meditation traditions vary in their approach on this point. In the mindfulness of breathing and metta bhavana practices, as taught here, I would recommend having the eyes closed. This allows for greater one-pointedness of mind. The exception to this is when you find you are tired, when the eyes can be opened to provide more stimulation.
The eyes should be lightly closed, with the muscles surrounding the eyes as relaxed and soft as possible. Even though the eyes are closed, you can think of having an “unfocused gaze.” This soft, unfocused state is more conducive to relaxation and mental calmness.