Is it bad or unhealthy to put my Mac to sleep? I am wondering if it is bad or unhealthy to always put my Mac to sleep or should I shut it down instead? What I mean by putting it to sleep is that the display and hard drive are sleeping.

The reason for asking this question is I have heard from several computer literate people that sleeping the hard drive is not good for it.
Anecdotally, the drives of 5 to 15 years ago would run longer if you never spun them down. When I managed servers - the drives failed less rapidly than the inexpensive hard drives that were in workstations (which typically spun down). It's not clear if we would have seen similar failure rates if we placed the higher priced (and presumably better built for the long run) drives in the workstations.

I have seen no credible studies that show any drive from the last 5 years lasting longer by disabling sleep. It's hard to imagine a case where you wouldn't want to have a computer sleep even if it were going to decrease the useful life of an inexpensive storage drive due to other components failing over time and the waste of energy.

We don't yet have good data on SSD wearing out either as OEM parts ordered from Apple or aftermarket SSD, but it will be interesting to see how they wear out due to write failures and if sleep writing of large RAM images will add up to enough writes to shorten the life of an SSD that otherwise would be healthy in the absence of storing sleep images.