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The twitching was your A/H's body's response to the decrease in his blood alcohol level. Remember, booze is essentially a depressent. As we aclimate to higher and higher levels of booze, our nervous system gets revved up in order to counterbalance the depressents effects -- to reach our own sick equilibrium. When the booze leaves our system, our nerves are still revved up. The result is involuntary tremors that you describe, anxiety, and some of the other sleep movements you have described. Withdrawl is the process in which we are regain our healthy equilibrium without the booze or the tremors.