Exposure to light helps to regulate the body's internal clock. This is why we get sleepy when it's dark outside and start to wake when it's light out. Research now suggests that it may be the colour of that light that really makes a difference.

Apparently blue light can disrupt our bodies' clocks. A Harvard-produced summary of blue light's impact on sleep reinforces the concerns of blue lights as a melatonin suppressor, citing two different studies about blue light, including one that exposed people to 6.5 hours of blue light and 6.5 hours of green light. The former suppressed melatonin production twice as long as the latter.

The summary also highlighted the potential to our sleep cycles posed by LED light bulbs, many of which can emit more blue light than bulbs have in the past.

On a very basic level, simply reducing your exposure to blue light before sleep should help. The Harvard summary mentions that avoiding looking at bright screens two to three hours before bed can make a difference, so that means minimising your phone, tablet and TV time before switching off the light.