It is often difficult to determine whether jerky movements of the limbs in a baby are a convulsion or a simple jerky movement which is perfectly normal in babies.. They can be differentiated by: Simple movements can be stopped by holding the limb whereas in a convulsion it will keep on occurring. Convulsions are associated with eye rolling so that you can see the whites of the eyes while in simple eye movements, the eyes may jerk but this white is not seen. Convulsions can occur at any time even when the baby is awake but simple jerks occur only during sleep. Convulsions last for some time but jerks are usually a single snapping jerk. After convulsions, baby will remain drowsy/groggy for some time, but with jerks they will show normal behaviour immediately afterwards. It is very likely from your description that this is a simple jerky movement. You can look up here: www.sph.unc.edu/oce/phnceac/babyguide/seizure.pdf http://www.babycenter.com/0_seizure_10907.bc?Ad=com.bc.common.AdInfo%40238da725 I hope this answer was helpful. If you need more information, feel free to ask. For accepting this answer, please click on the green 'accept' button below. Feedback/Bonus will be warmly appreciated.