Should you avoid blue light before bed?

When settling into bed, some might find themselves passing over a long-neglected book and reaching instead for a phone. They would not be alone. A survey of 122,058 adults, published in 2025, found 41 per cent used a screen every night in the hour before bedtime. Only 17 per cent reported no pre-slumber screen use at all. The adverse effects might not just be limited progress on War And Peace. A number of studies have linked evening screen use to a subsequent bad night's kip. Light from screens often has a lot of blue in its spectrum, leading some to suggest that blue is to blame for poor sleep. Retailers have taken note. A gaggle of products to filter blue light is now available, including glasses, software and screen attachments. But the evidence justifying such bias against blue hardly passes with flying colours.