Just like food, the type of light you're exposed to could make you feel better – or worse. Leading light expert Karl Ryberg explains how to max out on healthy rays at the darkest time of the year and avoid energy-sapping ones. Yes, it involves your phone...

Any products in this article have been selected editorially however if you buy something we mention, we may earn commission

It is my belief that good-quality light in our daily lives is far more important than we might think. Thankfully, the research is beginning to emerge to support my long-held views, which is gratifying, of course, but also of immediate importance to you. Enjoying the precious resource that is natural light will add so much more to your life: it will boost your reserves of vitamin D , but it will also make you feel so much better. And gaining insights into the role of electric light – and in particular, the blue light that now dominates our lives – will help you to minimise its negative effects too.

1. Be savvier with your screen time

Put simply, blue light from computers, smartphones and tablet devices affects the production of melatonin – the sleep hormone. And not only does it affect our sleep, it also affects our eyes. Doctors call the range of eye problems caused by computers Computer Vision Syndrome , and worryingly they estimate that as many as 50 to 80 per cent of us might suffer from it. However, there are very simple things that you can do to minimise the problems:

  • Follow the 20-20-20 rule. Look away from your screen every 20 minutes, for 20 seconds, at an object 20 feet away to give your eyes a break.
  • Blink more often. When many of us stare at a screen, without realising we forget to blink, making our eyes drier.
  • Fit your computer with an anti-glare monitor, or use your settings to change the screen to a shade of forest green. Deep green has a psychologically soothing and calming effect while still promoting focus. It also nicely replicates our ancient life in dappled shade. At evening time, go for orange, that restful glow that will make us feel sleepy. There are many ‘orange’ filters, such asf.lux.
  • Make sure your computer is the correct distance away from you. As a rule of thumb, it should be 50 to 100 cm from your eyes. If you find you can’t see at that distance, simply make the text size bigger.
  • Use the night-time setting on your mobile phone.

2. Reduce your flicker intake

We also have to be aware of the problem of screen flicker. The dimming of computer screens is only virtual, and done by so-called ‘pulse modulation’. This means that while the light level stays bright, it’s chopped up into small pulses to give you the illusion that the screen is darkening. You won’t notice it, because it all happens far too fast for the brain to detect, but your nervous system will still react to it. Here’s how you reduce your exposure:

  • If you’ll be reading a large amount of text, such as a report or even a book, print it out. Paper is so much more restful on the eye, and your brain will absorb the information more easily. The issue is a conflicting one because of the impact on the environment so do be mindful with your printing.
  • Set the light on your computer to a constant maximum to get rid of the flicker pulse. Avoid dimming the screen electronically, but instead use orange-toned sunglasses while using the computer. You might think that you look foolish in orange sunglasses, but looking a bit silly is a small price to pay for your eye health. Many outlets also now sell ‘blue-light blocking eyewear’.
  • Avoid watching movies on a TV or tablet if you possibly can, and settle for shorter shows if possible. Try not to binge-watch! Opt for the cinema if you must catch the latest Star Wars – it’s better for your eyes.

3. Use coloured light in the home

In a home setting, we think of ‘colour’ in terms of interior decorating – paint, furnishings and fabrics – but what about coloured light? If you think about it, we are surrounded by the reflected light of different colours bouncing off fabric, wallpaper or paint, but their luminous intensity is quite low. The coloured light coming directly from a lamp is much stronger and has a pronounced biological impact. A general rule is to add energising light colours to promote activity, and soothing hues to encourage calm, so bluish white light will make us feel alert and concentrated in an office or study, for example, but the direction of the incoming light is important. Bluish radiation must always come from a large surface overhead. Our old biological habits want the luminous heavens to be high above us – so fit bluish white lights above your workspace.

The bedroom is a great place to use orange light. Our brains have been conditioned to respond to this colour cue and start producing the sleep hormone melatonin, so feed yourself small doses of soft orange light before bedtime, ideally from a low-level light source that ‘washes’ the floor with an amber glow. Or, simply buy a low-wattage, soft orange light bulb and fit it to your bedside lamp. Alternatively, using an orange lampshade is the easiest way to achieve an amber ambience.

4. Up your white light

When Dr Norman E. Rosenthal and his team first discovered SAD , the answer to this light depletion was thought to be...well, light! But of a specific kind, which was then called ‘white light’. White light is simply the sum of all of the visible light in the spectrum, and Dr Rosenthal tried to replicate it using fluorescent tubes. He was essentially right: artificial light can indeed fool the brain into summer mode, but as electric light is far weaker than the sun, very long sessions were needed to stimulate the pineal gland (known as the ‘third eye’, which produces melatonin) into action.

Now, light boxes and dawn simulators are freely available, as well as desk lamps and even glasses. Bigger white boxes are certainly better, but avoid fluorescent tubes as they contain mercury. I prefer coloured monochromatic light to white light, as this works faster. Additionally, the SAD organisation in the UK has further tips to help you when deciding on what you need:

  • Make sure your SAD light box is ‘medically certified’, that is, certified by an organisation known as the Medicines and Healthcare products Regulatory Agency.
  • Make sure that it is of sufficient ‘lux’ to actually make a difference: 2,500 lux is the minimum, but you might need to spend longer with it to benefit; 10,000 lux is considered to be most beneficial, and your treatment time will be around 15 to 20 minutes every morning, sometimes longer. As a rule of thumb, the stronger the light, the shorter the treatment, but the greater the expense.
  • Bulb tube or LED? Cost may be an issue here, as LEDs last longer and you won’t have to replace the bulb tube as often. However, according to Dr Rosenthal, bulb tubes are more effective as LEDs haven’t been tested as much, so do your research!
  • Use your lightbox earlier in the day as otherwise it could keep you awake.
  • Newer research favours ‘blue’ light as opposed to ‘white’, due in part to shorter treatment times, but as SADA.org points out, blue light is not suitable for those with eye conditions, or those who suffer from migraines. If in doubt, check with your GP or with an expert in the SAD field.
  • Try before you buy. Many SAD light-box suppliers will allow a trial period to test the box – avail of this to make sure that this expensive purchase is absolutely right for you. Many people find light therapy helpful with SAD, but others find a course ofCognitive Behavioural Therapyuseful. Talk to your GP about what’s right for you.

Edited extract from Light Your Life by Karl Ryberg, published by Yellow Kite £16.99.  Buy your copy here .

About the author: Karl Ryberg grew up in Denmark and Sweden. He has degrees in architecture and psychology with a special interest in photobiology. He runs the Monocrom Institute for applied photonics in Stockholm and lectures worldwide on the creative use of light. His recent work takes light out of the clinic to give health and happiness to ordinary people.