The most common health problems among people who work with screens are three: eye strain, musculoskeletal disorders (back, neck, hands and wrists) and mental fatigue. The National Institute for Safety and Health at Work (INSST) explains in its guides how to prevent them. This lesson summarises its practical advice.
Why the discomfort appears
- Static postures for hours. The body is made to move.
- Poor postures: leaning the trunk forward to see better, twisting to avoid a reflection.
- Repetitive movements with the keyboard and mouse.
- Poor organisation: rush, lack of breaks, constant interruptions.
How to sit
- Adjust the seat height so that your elbows are roughly level with the desk or keyboard.
- If your feet are then not well supported and the desk does not adjust, ask for a footrest.
- Keep your back in contact with the backrest. The small curve of the backrest should sit at the level of your lower back.
- Move the chair close to the desk so you do not lean forward. The armrests must not prevent this.
- Use the tilt of the backrest from time to time to relax your back.
The INSST recommends a swivel chair with a five-point base on castors, with adjustments that are easy to operate while seated.
Desk, keyboard and mouse
- Leave a free space in front of the keyboard where you can rest your hands.
- Leave room to rest your forearm when you use the mouse.
- Choose a mouse that suits the size of your hand.
- The desk should have a matt surface and free space underneath for your legs.
The screen and the light
- Place the monitor in front of you, or at most within an angle of 120 degrees horizontally, so you do not turn your neck or trunk again and again.
- Position the workstation parallel to the windows: to the side, not facing them or with your back to them.
- Use curtains or blinds depending on the time of day.
- Adjust the brightness, contrast and text size. Keep the screen clean.
Laptop
A laptop used all day worsens the risks, because screen and keyboard come together. The INSST's guidance for remote work advises a separate keyboard and mouse and, if possible, an external screen. Working on the sofa or in bed is not a suitable working posture.
Breaks and movement
The INSST states that short, frequent breaks are more effective than long, rare ones. As a guide, it suggests breaks of about 10 or 15 minutes for every 90 minutes of screen work, and at least one of 10 minutes every hour in tasks that demand a lot of attention. The collective agreement or the employer may specify them. They are better if they are active: gentle neck stretches, a few steps, a change of posture.
To rest your eyes:
- look into the distance from time to time;
- do the palming exercise: cover your eyes with your palms, without touching the eyelids, for 20 or 30 seconds;
- alternate screen work with tasks that put less strain on your eyes.
When to ask for help
If the discomfort lasts, do not wait for it to pass: see your doctor or your prevention service and tell your employer. This is a right provided for by the display screen decree.