Why does Apple's mobile phone always light up when it receives text messages?

Because the "Never Lock Screen" function is turned on, just adjust the screen lock time in the settings.

Take the iPhone7 mobile phone as an example, the specific operation is as follows:

First, open "Settings" on the phone desktop.

Second, open the "Settings", find the "General" column, and click to enter.

3. Click "Auto Lock" in the "General" interface to proceed to the next operation.

Fourth, finally check the appropriate "screen lock time".