Grayscale phone: does a black-and-white screen cut screen time?

What the trial found

Researchers asked 51 medical students to spend one week with their phone in colour and one week in grayscale, in alternating order, and to read their screen time from the phone’s own tracker. In the grayscale week, average daily screen time was about 28 minutes lower, whichever week came first. The authors note that some tasks were harder in grayscale.

Its limits

• Small and short: 51 people, one week each.
• One group: students at one medical school.
• Not randomised: the order followed the order people signed up in.
• Preliminary, in the authors’ own word. It shows the idea is worth testing at a larger scale.

How to turn it on

• iPhone: Settings, Accessibility, Display & Text Size, Colour Filters; switch on and choose Greyscale (Color Filters and Grayscale in US English). Add it to the Accessibility Shortcut (a triple click) to switch quickly when you need colour.
• Android: on many phones under Digital Wellbeing (in bedtime mode) or under Accessibility (colour correction or grayscale); the names differ between makers.

Colour matters for maps, photos and some apps: the shortcut keeps it a click away.

Grayscale and other habits

Grayscale makes the phone less inviting; it does not change why you pick it up. It works best with the other steps: notifications from people only, the phone outside the bedroom, phone-free meals. More in how to use your phone less.

Fewer reasons to unlock

Many pickups are for something small: the time, the next meeting, whether an email came. Lychnos Ring is being built to answer those on your finger, with a single line on its screen and the rest at your ear, so there is less reason to unlock the phone at all. It is in development.

Source, read 4 November 2026: Hagerty and others, “A cross-over feasibility trial of smartphone grayscale mode in medical students”, Frontiers in Digital Health, 2026.