Hi ! I get low-level headaches 24 hours after I practice. I love practicing so I don't want to give it up, but it's not terribly encouraging to feel lousy for a day after a session. Can anyone help me to get this figured out? Thank you !

Maybe you've been putting too much pressure on your neck, causing a cranial or cervical spine torc. I'd strongly recommend you find someone versed in cranial/sacral work to take a look at this. Second best would be a chiropractor. I think you're getting the headaches when you're asleep is because you're muscles holding your head to compensate for some pinch or injury are releasing, permitting the nerves to freak.

You should be sure you are drinking plenty of water and restoring your electrolytes. Especially if you are practicing hot yoga.

Hanuman

I agree with Hanuman, I think it’s important to hydrate. But it’s also good to make sure that you are not whipping your head around too much when you come up to standing from forward bends. Try to keep you neck and head as an extension of your spine the entire time you practice. When you do Rabbit Pose in Bikram make sure you put the weight mostly in your shins instead of in your head.