I myself have bloodsugar issues, so I often shake after eating, when I haven't eaten in a while, and sometimes when I wake up or before I go to sleep. These shakings are results of my blood sugar fluctuating. You should ask your doctor to test and see if you have blood sugar issues. That may be the cause.
i have never done drugs before, but it has happened to me before i was just about to fall asleep and then i just had like a full body twitch, i was told that it was because my body thought it was dying, but i don't believe that for a second.
It's your mind going in to an unconscious mode while the other half is still conscience half of you is ready to dream the other is still awake this always happens to me too just relax and breathe when it does
Interesting...I have had them all my life, and did not know there was a name for them! So I googled "sleep starts," and learned that they happen to 60-70% of people! However, I did not find a really good explanation for them...supposed to happen more in the elderly, which I am now, but I had them more as a child and young adult than I do now.