When you get up after a long session of using your laptop how do you feel?

Stiff neck? Achy shoulders? Twinges in your lower back?

These are all signs that your laptop, or rather the way that you are using it, is hurting you. If you keep on using it that way there is a risk that those aches and pains will turn in to a permanent injury. Fortunately, it is easy to avoid the problem by making a few small changes in the way that you use your machine. Read on to find out how.

Laptop ergonomics

From an ergonomics point of view, using a laptop on your lap is close to the ideal thing to do. The position allows you to recline slightly and this means that, with your hands comfortably on the keyboard, your head and neck are in a naturally comfortable and relaxed position.

Contrast this with what happens when you put your laptop on a standard height desktop. You have to sit forward and, with your hands on the keyboard, usually need to duck down to see the screen clearly. Sitting forward is bad for your back anyway, but the added distortion involved in ducking down means you could be setting yourself up for some real problems in the long-term. Ouch!

Three big problems

So, using your laptop on your lap is the best thing you can do from a back health point of view, but doing this does present some problems. I think I could go on expanding this list for some time, but here are three immediate examples:

Bottom view of an Acer laptop showing the cooling system intake

  1. As soon as you set your laptop down on the top of your legs you will most likely block off the air intake grills (2) to your machines cooling system. Starved of air, the machine will quickly overheat. This threatens to cause actual damage to the electronic components inside the laptop, but before this happens it is more likely that it will become so hot that you will be forced to remove it.
  2. Putting a laptop on your lap means adopting a knees together posture that causes another potential problem for men. We are just not built to spend time sitting this way, and it has been suggested that local overheating could damage male fertility.
  3. Laptop computers are a source of electromagnetic radiation at a wide range of frequencies. Modern machines operate at around the same frequency as your microwave oven does and they have built in radio transmitters for wifi and Bluetooth. None of the machines I have examined have had any significant shielding, and it is common to locate the wifi antennae right at the bottom of the machine. There is no evidence that these signals are strong enough to cause any harm whatsoever, but some experts think it is wise to work on the precautionary principle and I am inclined to agree.

Do not leave the bottom of your MacBook Pro in contact with your lap or any surface of your body for extended periods. Prolonged contact with your body could cause discomfort and potentially a burn.

Apple MacBook Pro Manual

So, what is the solution?

eTray laptop tray with Acer laptopWell I guess you must realise at this point that I am probably going to say to you that you should get yourself an eTray laptop tray. Its true, I am going to suggest that, but eTrays are not the only solution so I should explain what I think you should be looking for.

The worst thing you can do is to insert a cushion or similar between you and the machine to provide some insulation. The air intake will still be blacked and the overheating will continue, but now you won’t be aware that is happening until it is too late. If the machines does get damaged you might find that the manufacturer is reluctant to honour the warranty and that might mean a very expensive repair bill.

Nor do you need to buy an elaborate gadget with built in fans. The laptop’s cooling system will work just fine on its own as long as you keep the ventilation slots clear. The fans are noisy and require power from somewhere to work. That usually means you have to plug them in to a USB port where they will take power from your machine’s battery. Even if you are running off the mains adapter that will cause additional heating, and there if there is any benefit this will most likely neutralize it.

The laptop needs to be placed on a flat surface so that its feet can maintain a clearance (usually only 3 or 3 mm is required) that will allow cool air to reach the intake grill. Nothing more is required to keep the machine happy, so you could use a piece of plywood or MDF, or even a large book and you would have a solution. If you use one that is big enough then you will have space for the laptop and room for a mouse.

Of course using a board in this way is going to get a little uncomfortable after a while and the machine will still produce some heat in normal operation. Putting a cushion of some kind under the board will make it more comfortable and provide some insulation from the machine.

The question of what to do about electromagnetic waves is a bit more complicated and needs some explanation. The problem and solution are summed up pretty exactly by the old phrase “you need a long spoon if you are going to sup with the devil”. Electromagnetic waves obey what is known as the inverse square law, which simply means that the amount of energy they contain reduces considerably with distance. You will never get completely away from them if you use computer equipment, but you can reduce your exposure by adding some distance.

Even short distances make a considerable difference and the spacing you introduced by putting a cushion under the board will have reduced your exposure considerably. You can reduce it even further by introducing some shielding that will reflect electromagnetic waves.

Cross section of eTray laptop tray showing the main components

For eTray we use a sheet of heavy duty aluminium foil which is located directly under the centre of where the laptop will sit. It’s not a complete solution, but it will reduce heat transfer and interrupts the direct path for wi-fi signals between your notebook and your lap. You can get a similar effect with something as simple as kitchen foil.

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