Assuming you are getting enough sleep on a regular schedule, try to precede your meditation period with a light workout, like some stretching, pushups, situps, jumping jacks, or maybe some work like cleaning. I often do this, even when sleep is not an issue, and find that my meditation is often much more clear and peaceful... more insightful this way. Don't overdo it though, strenuous exercise before meditation leads to it's own difficulties.
I am also in the sleep when sleepy camp. However, to ensure I am not indulging, sometimes I will try to meditate anyway, then when I catch myself waking up as I am starting to tip over on my cushion, I will lay down on the floor (slightly uncomfortable instead of on my comfy bed) and just sleep 10-15 minutes. Often when I get back up, my meditation is rather strong.
Sotthī hontu nirantaraṃ - May you forever be well.