This is of course different for each person. Watch the videos on this page and you will see that even a 2 hour session can do wonders. It all depends on the state of you body at present and how much healing you are seeking.
If you are very ill, it is better to begin slow with a 2 hour session and gradually increase the hours spent in the EE Room over time. This is due to detox that takes places and why Sea Salt baths after every 12 hours in the EE Room is equally important to flush out the toxins.

