In our lactation management courses at TDH, we teach early and late hunger
cues.  Early hunger cues are lip-smacking, tongue movements, sucking on
hand, wiggling around.  late cues are fussiness and latest cue is crying.
We also talk about phases of arousal - eg deep sleep, light sleep, quiet
alert, active alert, crying.  Latching on is most successful in the quiet
alert phase, and the early hunger cues happen then.  Some babies start
these in the light sleep phase.
Julie Graves Moy, MD, MPH
Austin, Texas