What could be causing session values to be lost after a certain period of time in PHP?

Session values may be lost after a certain period of time due to the session expiration settings in PHP. To solve this issue, you can adjust the session.gc_maxlifetime value in the php.ini file to increase the session timeout period.

// Increase session timeout period to 1 hour
ini_set('session.gc_maxlifetime', 3600);
session_start();