When I first wake up, it takes forever to get warmed up on the guitar, or any kind of physical action. The simplest solution to this is to take a HOT BATH!! This warms up your body (literally), which loosens up the muscles/tendons, etc.

I used to take a shower before I went to sleep to shorten morning preperation time for school/work, but some nights I'd just be too tired and go to sleep. Waking up, I was going to take a shower, but I was too tired to stand up so I took a bath, instead (I'm not a morning person :) It felt great, and I realized I was a lot looser than when I usually woke up, so I've been taking morning baths ever since.

A note to guys: Contrary to popular belief, taking baths instead of showers does not in any way lower your level of masculinity unless you tell your friends ;)