Dogs do need to chew as a way of 'winding down'. Its a calming thing for them. Our 4 year old American cocker spends a good 15 minutes chewing one of his rope toys before he goes to sleep. Its perfectly natural, the difficulty comes if they're chewing things that you don't want them to.
We rotate the toys every couple of weeks to keep them interesting. You can also try using stuffed kongs (if you freeze them it keeps the dogs occupied for longer
).
Whenever Amber (12 months) is chewing something that I don't want her to, such as the stairs I just say 'no' in a 'I mean it' tone of voice, but then give her something that she can chew instead.
Hope this helps