Is it advisable to power down CDP/Transport?


I am wondering if it is advisable to power down CDP's / transports when not in use. A very knowledgeable friend of mine mentioned that the laser life will be impacted if left on. I have never shut a digital piece down -- perhaps I should. The concern is only relative to the equipment prematurly wearing out. Any thoughts?
jeffga
Hopefully the pickup design turns the laser off when not actually playing, but who knows this for certain? I've always wondered about this especially since I had to have an aging pickup replaced, which wasn't cheap. This EAD machine never fully powers down; it goes into standby mode when the power button is turned off, which it should for better sonics vs. coming up stone cold. I guess the power switch only turns off the display on this one?
Laser would not be on unless the drive were engaged (i.e. actively reading a disc- not in pause or stop). I think this is right.