The immobilisation thing sounds like sleep paralysis.
When you sleep your muscles go into lockdown to prevent you acting out your dreams. When this fails you get people sleepwalking. Sleep paralysis is the reverse - your muscles are still in deactivation mode for sleep, even though you've woken up. It's often accompanied by feelings of terror by people who don't know what's happening to them.
( Bob Todd whee, Fri 4 Jul 2008, 10:15, Reply)