Why does my MacBook Pro fans make loud noise when it's on my laptop in bed?

Hi JoeyDee;

Probably because the bedding is not allowing proper air flow. Personally I would stop using it in this fashion.

Allan

aside from blocking air ducts, the bedding is a good thermal insulator, so it is reducing the amount of heat the mbp can dissipate through its base

Laps can cause it to run hot too. The computer's aluminum case is part of the heat dispersion system and works better as more is exposed.

Look at lap desks. You could make one from a scrap piece of plywood. Here's a commercial version that has a "bean bag" on the bottom to contour to your legs:

http://www.organizeit.com/polaptopdesk.asp

Joey, the best thing to do is to put it on to a flat hard surface or purchase one of the many accessories that allow you to place your "Portable" as Apple calls their products on your lap. Main reason they don't call them laptops is because of the fact that they are not meant to be put on your lap.
There is a product that you can find on the Apple Store, but this is the designer site too http://www.raindesigninc.com/ilap.html

Personally, I place a large textbook between my lap and the laptop. It works perfectly to keep from uncomfortable heat and allowing air flow!

NiceGuy_83 wrote:
your "Portable" as Apple calls their products on your lap. Main reason they don't call them laptops is because of the fact that they are not meant to be put on your lap.

True. If you look at many companies making "laptops," they never call them that anymore. They are now called "notebooks" or "portables."

MacBook Pro heat control definitely depends on the bottom plate being able to vent. You shouldn't use it on a carpet or upholstered chair either. Any flat surface that allows even a little air to pass under the bottom case will help it disperse heat as designed.

When I do have to use it on my lap, I try to leave some space between my legs. This allows more air to pass under the case, and also helps keep my legs from being under the hot center of the case.