How do I adjust the session timeout

To change the default session timeout (which is 60 minutes) you must edit the file web.xml. For EAR/WAR installation, this file can be found in <YOUR DEPLOYMENT>/confluence/WEB-INF/web.xml and for a standalone instance, the file is located in <YOUR CONFLUENCE INSTALLATION DIRECTORY>/conf/web.xml

The element you want to edit in the web.xml file is:

<session-config>
    <session-timeout>60</session-timeout>
</session-config>

The value within the session-timeout tag defines the amount of time the session will exist, in minutes.

Note that after editing the web.xml file you will need to restart confluence for your change to take effect.

On a related note, to configure Confluence's internal connection pool timeout period, please tweak the c3p0.timeout property in your <Confluence-Home>/confluence.cfg.xml file:

<property name="hibernate.c3p0.timeout">30</property>

This value is an indication of the number of seconds a connection can remain pooled but unused before being discarded. Zero means idle connections never expire.
More details can be found here.