HOW TO... Save your eyesight while reading in bed

摘要

There are few greater joys than snuggling up with something to read at the end of a busy day... unless you're using a smartphone or tablet. Humans are simply not built to use that kind of technology before bed. Here's why: the quality of light changes throughout the day. In the morning, when we're preparing our bodies for the day ahead, natural light can be 'colder', with hints of blue. In the evening, as we wind down and get ready for sleep, it's 'warmer', and characterised by orange, yellow and sepia tones. Thus, our brains have evolved over millions of years to associate cold light - like the light produced by an LCD screen - with being alert and awake. This is why reading from a tablet or smartphone immediately before heading to bed can interrupt your sleep cycle.