Mastidonalation
Is a partially involuntary action by a human when the neck and head is in an unsupported position and the individual is falling asleep. The action happens when the neck of a person relaxes and allows the head to drift to a position mostly determined by gravity and then suddenly repositioned to a somewhat supported or upright position by a semi-wakened mind. The action is repeated over and over until the person is either wakened or falls totally asleep.
Mastidonalation is when my wife is sitting in a chair and watching her late night movie. She struggles to stay awake but here head keeps bobbing up and down while she drifts in and out of an unconscious sleep state and a semi conscious sleeping state.