8 weeks old baby nursing for two hours

My baby is around 8 weeks old, during the day when I breastfeed him, he will nurse for thirty min then start to fall asleep and I will pull him off the nipple and he will be alright for two hours without showing signs of hunger(rooting, smacking of lips etc). However, when it reaches around 6pm or so, he will latch for one to two hours but still appear hungry after that and cries. Anybody experiencing this? It's so tiring to latch him so often