Why do you twitch in bed, when your about to go to sleep? not just before.. but when your still awake in bed? leg and arm twitches

Myoclonic jerks: Do not worry, it is common and widespread. If you are asleep and it awakens you, then this is termed periodic leg movements in sleep (aka , nocturnal myoclonus), which should be treated with a medicine. Otherwise, no real problem or concern.

Myoclonic jerks: Myoclonic jerks are common. Stimulation of the muscle in little bursts makes the muscle jerk. It's part of the reflex arc and normal.