20 month year old. she tends to 'jerk'/'twitch' a few times as she dozed off to sleep (most nights) next to me. no other symptoms or odd behaviours. concerning or not? thanks kindly

May be low Magnesium: I can understand your concerns but most likely this is not serious. A common cause of jerks and twitches is magnesium deficiency, which is very common. Try giving (or getting her to eat) foods rich in magnesium, which tend to be dark leafy greens, nuts, seeds and beans. See http://www.whfoods.com/genpage.php?tname=nutrient&dbid=75 for details.