A laptop is a compact computer and has small components and has very less gaps for ventilation and cooling as compared to a desktop. It has fans that help in throwing the hot air out as well as letting the fresh air in (due to gaps between the blades of fan). These fans are typically at the vertical back and bottom of the laptop. Now, when you are using a laptop on a bed, the flat surface is not hard and if the bed has pillows, quilt, bed sheets etc. blocking the hot air being vented out, you can easily analyze what will happen to the inner temperature of the laptop. The situation of hot air being blocked from your laptop due to unnoticed stuff lying close to your laptop on your bed is extremely dangerous as it leads to overheating of the inner parts of the laptop. I am sure this is not a very technical thing to realize. This overheating of the electronic parts in the laptop can definitely damage the parts of the laptop or cause a fire too if it continues for a long time (few minutes to hours depends on how compact your laptop is and how much heat is being blocked). I have heard of cases of start of fire due to laptop getting overheated due to blocking of the released heat, when used on a bed having stuff obstructing the intake and throwing of heat. Thus my advice to all laptop users would be to avoid using laptop on a bed. If you have to use your laptop on bed, then make sure that the laptop fans passage for exhaling hot air and inhaling air is clear. Also use a laptop inner temperature monitoring software which is normally supplied by the laptop manufacturer. You can also download it from Internet. Using the computer temperature monitoring software will let you know the audio or visual alarms in case of a condition where the temperature of the inner parts of your computer increases too much. Using a laptop inner temperature monitoring software can help you in taking a corrective action in case it is needed. One such free software that monitors the temperature of various parts of computer is SpeedFan. You can also use a laptop Fan Control software. Do a Google search for the mentioned keywords and download the relevant software that suits your laptop model. If you still want to use your laptop on the bed, then use a laptop stand or make sure that the fans of the laptop are getting a clear path for air (intake and exhale).I am sure that laptop users will find this post on avoiding the use of a laptop on an uneven and soft bed extremely useful! Even using a hard board below the laptop when using it on a soft bed would help. It would help in passing of the heat through the vent and the air gap between the hard board and the laptop bottom (good word Isnt it?) Take care of your laptop and dont ever let it overheat. Take care that the vents of your laptops are never ever blocked otherwise it can become a frying pan and go up in flames. I know that no one sane enough would like it to happen ever! Right?