87% of Britons say they look at their phone or tablet within an hour before going to bed. On top of this, 74% of people keep their phones in the bedroom at night. The downsides of digital nightcaps The blue light emitted from your device’s screen is part of the light spectrum most active in your sleep cycle. Sleep deprivation has been linked to a myriad of physical health issues, including high blood pressure, heart disease and obesity.