This is your body trying to tell you it's desperately time to stop bombarding it with methamphetamine and let it heal. Well not technically that but you're obviously heavily addicted, not trying to patronise you, but its likely time to begin to start thinking about giving things a rest and getting some help if you need it.
So you only do meth a couple times a week? I am kinda confused about your question.. Are you asleep the entire time the rest of the week you aren't doing meth? It could be that your brain is lacking dopamine when you are not high, which will make you tired and sluggish.
My advice would be to lay off the meth for a while. Even if you are not addicted, regular meth use will take a serious toll on your brain and body. I would take a month or so off of it and let your brain heal. Maybe take some vitamins/supplements as well. Make sure you eat properly, try and get some exercise, and sleep well.
Ok man, this is kinda like saying you took Heroin reguarly for a month or so and you have noticed that you always seem to get sick when you don't take it. Seriously dude, if you can't figure this one out, you should NOT be doing meth, ever...
No offence man, but you gotta know what you're are putting in your body and what you can expect.
I dont' really see this going anywhere. So I am going to close this.. PM me if you can think of any reason why it should be re-opened and I'll discuss it with the other staff members.