Every user will have a session created upon login, this session remains active for 2700 seconds from the last action you make in the application. If you are using the application continuously, this limit does not affect you. After 2700 seconds of inactivity, the system will ask you to log in again as a way to prevent unauthorized access.
To change this session limit, you can click on Account Settings at the top of the page. Then click on User Preference. enter a new number for Session Timeout . The maximum allowed is 28800 seconds which is 8 hours. Save the preference . To activate this new limit, you would need to log out and log in again.