Pants diapers leaking

Hi mummies, sos please. So, so stress out. 😭 My 18 month old toddler was wearing Huggies Naturemade Pants size L (he's 9.8kg) and it keeps on leaking everytime he sleeps at night, eventhough I've changed his diapers before he sleeps. I got sooo stressed up I change to Huggies Silver Pants size M (downsize into thinking previous diaper was too large) but still the same outcome. I've just bought it and it leaks again! What should I do? 😭 #stress #pleasehelp