jet lagged baby

We're back in NJ from Yokohama and this time around, Terran's jet lag is worse. It's been 5 days since we've been back in he is not adjusting. Even worse, he is taking little naps of 4 hours max and no continuous long sleep. Last night, he was up from 9pm to 4am. with a 30 min nap in the middle. We've been getting up and playing with him at night but we are changing tactics today and making him stay in bed. I go to him every 15 min or so to try to calm him down and encourage him to sleep but so far, it's not really working. During the day, he doesn't sleep much either. At most his regular naps. We go out to the park and play and try to stay out in the sunlight. I wonder when it's going to end.... I google for "baby jet lag" but there's really no real advice. tired....