I have known of more than one cruise that didn't go well when someone used to a structured life found endless free time and rum or other substances. There are a few ports that seem to have a lot of these cases.
I totally get the sunrise to sunset thing though. Assuming you aren't just sitting on your ass, a day of up at dawn and swimming/diving/hiking followed by a nice dinner with a dark n stormy has me ready for bed for sure.
My one question is what does he do all day? Sure, going down to the market to pick up a fish and a beer is fun on day 1 and day 20, but what about on day 120? He says he goes to sleep at sundown and wakes at sunup. This means that in the tropics he is in bed for nearly 11 hours a day. If he was actively sailing around the world or something, I would understand that he is busy. And if he was writing a book I'd say he has a job. But does he just stare at the ocean all day, every day.
I keep thinking back to the Andy Griffith show when Howard retires to a South Pacific Island. He walks into the local store and sees some very old men with long beards sitting on the bench mumbling to eachother. The proprietor says something like, "they where just like you. They moved here two months ago."