Prometheus News


Could better light help you survive winter?

Dec 8, 2019 by Hamza Sheraz.

Being clever with light may help you get more sleep, feel more awake and stay energetic all winter, discovers Brigid Moss.

Think back to last winter. Did you have to drag yourself out of bed every morning, feel down, dreary, sleep too much or too little? You could self-diagnose this – light deprivation. That’s the theory of Karl Ryberg, Swedish light expert and author of new book Light Your Life. In his native Sweden, he’s been treating people using light therapy for over 20 years. The reason is brains need quality light for their best function. Having evolved at the equator, our bodies just don’t get enough light in the darkness of a northern winter. Electricity is a poor substitution, he says, as our brains crave sunlight. “Your entire biology is coded to it. The body recognises it.” If you think that we spend 90% of our lives indoors, commuting before light and after dark, it’s not surprising most of us end up feeling rubbish. “Reduced levels of sunlight, particularly for those of us who live at some distance from the equator, can disrupt the biological clock and can also cause our serotonin levels to drop,” says Ryberg. The most extreme form of light deprivation is seasonal affective disorder (SAD). “Not all of us experience depression or stress, thankfully, but it is my belief that good-quality light in our daily lives is far more important than we might think.” Here’s how to stay switched on, all winter long.


During your lunch break, get out. Noon is the best time, when the sun is at its highest and brightest. The quality of sunlight, even filtered through clouds, is better than any electric source. Even 10 to 12 minutes will make a difference, although 20 is better. “The volume of a winter sky is so huge, even if it’s a rainy day or the light level is low you’ll get the amount of daylight you need to reset your body clock. The European standard says that in a good office you should have 500 lux (unit of luminance) on your desk, but if you go out even on a grey day you easily get 1000 lux.” You may think your office light is fine, as it has lots of windows, but the anti-glare screens that are usually fitted will block some important parts of the light. Oh, and try to ditch the sunglasses (except in the snow, for glare).
'Blue light stimulates the brain into wakefulness; it’s the colour of a summer sky'


Ideally, your home or office lighting should mimic natural light. “There are many qualities of white light,” says Ryberg. In the morning, the light you use should be more blue white (often called cold white on bulbs). “Blue light stimulates the brain into wakefulness; it’s the colour of a summer sky,” he says. Towards the evening, light should become warmer, more golden (warm white bulbs). “Sunset, candles, a campfire signal to the brain that it’s night time, time to go to bed.” You can do this by fitting your bedside lamp with a low-wattage soft orange bulb or an orange lampshade. Note: be sparing with candles when the windows are closed, as they use up a lot of the room’s oxygen.


As you’ve probably heard, screens stop you sleeping, whether it’s your phone, TV or computer. That’s because the light from screens is very blue, so stops the production of the sleep hormone, melatonin. Just turning down the screen isn’t enough – low-level screens produce flickering, which the brain doesn’t like. In the evening, it’s better to switch the screen to an orange filter, with a software filter such as f.lux, or use orange-toned sunglasses. You might look weird, but you’ll probably sleep better. Use the night-time setting on your mobile, too.


It’s natural to want to hibernate a little in winter, and you should follow the rhythm of your body and do it, says Ryberg. “We should get more sleep in the winter but we don’t get it, maybe an hour or two more ideally.”


Light boxes do work to prevent the symptoms of light deprivation, although they’re second best to spending time outdoors. “It’s still not sunlight or daylight, but it’s a decent imitation,” says Ryberg. The alarm-clock type is “probably the best one,” he says, “as it helps you slowly wake up with the light, which is how we should wake up.” If you are using a regular light box, use it pre-noon and look for one that’s 10,000 lux, ideally. “The stronger the light, the shorter the treatment.”


The Scandinavian style is designed to maximise light – light-coloured walls and floors – although you may want to keep in warmth with heavy curtains; make sure you draw them properly. And washing your windows can increase the amount of light coming inside noticeably. “Get in the few photons that you can in winter,” says Ryberg.


Don’t use brighter lights than necessary at home in the evening and sleep with the lights off, ideally with heavy, tight-fitting curtains or blackout blinds. Either switch off any devices with standby lights or cover them with masking tape. Light Your Life by Karl Ryberg is published by Yellow Kite.