My son is 21 months old. he rolls his eyes once or some times twice in a day. Sometimes he blinks both eyes first 3-4 times and then immedatedly rolls eyes up for a second or less. His eyes go up while sitting, in arms and even while walking. it lasts for less than or just a second. If we see him do that and call for him,or shake him, he responds sometimes and some times he doesn't. He otherwise while playing as well doen't respond many a time so we can't tell the difference. If we don't call him, he would do that and then continue playing or doing what he was. We have never notices he doing this and going out of balance or falling down or any other symptom like fists becoming tight simultaneously. He is otherwise a normal kid but often gets excited. I am worried about this 'eyes rolling' thing. I need to know if it is an indication for something serious. please advice. Thank you.