Ten minutes before bed

Ask a group of fifteen-year-olds how they fall asleep and most will describe the same scene: lying in bed with a phone, scrolling until the eyes close by themselves.

Two separate things make this a poor way to end a day. The first is light. Screens held close to the face send bright light into the eyes at the hour when the body is preparing for sleep, and that light delays the release of the hormone that makes you drowsy. The effect is modest but real, and it adds up across a week.

The second is harder to fix. A feed is designed never to finish. There is no last page, no credits, no natural moment to stop. Anything that has no ending is difficult to put down, because putting it down is always a decision you have to make yourself rather than a decision the thing makes for you.

The suggested fix is not to give up the phone. It is to give the evening an ending the phone cannot provide. Ten minutes of something that finishes — a few pages of a book, writing three lines about the day, tidying the desk for tomorrow — gives the brain a signal that the day is closing.

Students who try this often report that the first three nights feel strange and the fourth feels normal. That is roughly how long most small habits take before they stop requiring effort.