I've had a laptop in the shop for at least 10 years.
This one for the last 7 years and had NO problems because of the environment.
The first one rode around on my tool truck for 6 years as a business computer before I brought it in the shop.
Every once in awhile I wash off the screen with water and blow the dust out of the keys with the shop air compressor.
My son, who sells and works on computers, CRINGES when he sees the condition of my machine.
He also recommends that I turn it off at nights but, I figure that I may wake up at 3:00 AM and want to see "face book" with out "warming up" the screen. So, I just leave it on and close the lid so it can get a bit of sleep at night.
As you can see, I wouldn't worry about it!
Rog
PS The first one was a Panasonic and the current one is a Toshiba running Windows 7.