Awake baby

So my baby now between 3-4 weeks old often has long periods of awake time.. usually around 2.5 hours in between naps in the day time and then in the evening sometimes up to 4 hours before I can get him to sleep again. I've read babies his age shouldn't be awake longer than 90 minutes. But he will not settle no matter what I do. Is this really bad or is it common that babies his age are awake longer than 90 minutes? Also any advice for getting him to sleep?