Another minor problem that may affect babies is “myclonic jerks.” Even if you're not familiar with the term, you're undoubtedly familiar with the event. It's likely happened to you yourself. You're in bed, you're half asleep or more so, and suddenly your body or part of your body twitches or jumps in place as you lie there, and you wake up with a start. They happen to babies, too. But while you know what it is or at the very least know that it's nothing serious, a baby will be more easily startled by such an occurrence. If you experience a myclonic jerk and you have trouble falling right back to sleep, you may be momentarily upset at this intrusion into your near-sleep state, but you won't start crying. But you're not six weeks old or six months old or sixteen months old.

So if you put your baby to bed for the night, he seemed to be drifting off happily, and a short while later he's crying again, consider that the problem may well be that he has experienced a myclonic jerk and now is suddenly and unhappily awake again. It's nothing for you to be concerned about. If only you could explain it to him, you could let him know that it's nothing for him to be concerned about, either. But it will require him soothing himself back to sleep again, perhaps with a bit of help from you.

Besides “motor sleep starts,” as myclonic jerks are sometimes called, there are also “visual sleep starts,” in which the sleeper has the sensation of bright light suddenly flashing inside the eyes or inside the head, and “auditory sleep starts,” consisting of a loud noise, something like a snap, which seems to emanate from inside the head.