"They wake up in the morning."
It isn't necessary and as a native speaker, I find that there aren't many opportunities in which I would use it in my normal speech. However, say there are two groups of people and you want to differentiate which group of people wakes up in the morning. I personally would say "Wao wanaamka asubuhi" while pointing or gesturing towards the group that I am talking about in order to avoid confusion of which group I was talking about. That was a long explanation, if you want me to explain further, or give some more examples I can. :)