Does Blue Light Affect Our Circadian Rhythm?
Our eyes are not very good at blocking blue light, so most of it passes straight through to the back of the retina; this helps our brains translate light into images (WebMD).
Blue light is prevalent in sunlight, so your body naturally absorbs the most during the summer and much less in the winter. Because of this, the researchers suggested that adding blue light to indoor atmospheres, as opposed to the standard yellow lights, which are typically used, may help boost mood and productivity year-round.
‘Exposure to all colours of light helps control your natural sleep and wake cycle, or circadian rhythm. However, exposure to blue light at the wrong times of day can interfere with your body’s ability to prepare for sleep because it blocks a hormone called melatonin that makes you sleepy (WebMD).
LEDs appear to emit a bright white light, but in fact, LED lights contain high amounts of blue (in the 400-490 nm range). This blue light exposure is responsible for increased alertness and cognitive function, which can be useful for shift workers as they go against their natural body clocks schedule and need a bit of extra help to adjust. Studies have shown how blue light can help treat seasonal affective disorders such as SAD, increasing the amount of bright light in the darker winter months, replicating the amount of light exposure typical in British summertime.
A study from the Light Research Program at Thomas Jefferson University in Philadelphia found that blue light strengthens and stimulates connections between areas of the brain that process emotion and language. This means that blue light may, in turn, help people to handle emotional challenges better and regulate mood over time.
Blue light (wavelengths from 460 to 480nm) is very beneficial in the mid-late morning to wake us up and during the daytime to make us feel alert. It has even been linked to people making fewer mistakes and improved wellbeing. It is the overexposure to blue light that begins to cause issues. It is particularly disruptive at night when it induces the strongest melatonin suppression.
When people read on a blue light-emitting device (like a tablet, rather than from a printed book) in the evening, it takes them longer to fall asleep; plus, they tend to have less REM sleep (when dreams occur) and wake up feeling sleepier— even after eight hours of shuteye (National Sleep Foundation N/A).
However, small changes can be made to avoid the amount of blue light exposure in the evening. You can adjust your laptop/computer screen brightness and colour so that the colour moves away from blue to more of a reddish/yellow tone after a certain time. Also, using warmer coloured bulbs in bathrooms and bedrooms help to minimise the impact; red light has a higher wavelength; therefore, it does not suppress the release of melatonin.