Sit, or lay down (if you know you can remain awake), in a comfortable position, keeping your spine straight. Close your eyes.
Imagine your body getting lighter. Imagine that a gentle wave of cool water is washing over your body, beginning with the top of your head. Let the coolness wash all around your head. Feel the coolness bringing peace to your head as it washes away all tensions and worries.
Now, allow the coolness to wash down your neck and shoulders. Peace is washing over you and you feel yourself growing more and more relaxed.
Let the coolness wash down your arms to your fingertips. Let any tension flow out through your fingertips, disappearing forever.
Now let the cool water wash down your chest and back. Feel the coolness and relaxation wash over your belly and down your thighs.
Let the coolness wash down your knees and calves and then your feet and toes. Let any remaining tension flow out through your toes, disappearing forever. Now, you are completely relaxed. The purifying, cool water has washed away all worries, stress, and tension.