Mood changes on IF

I have been doing 18:6, 5 days a week for about one and a half months. While working, and being physically busy, IF was so easy to do. As soon as work was less scheduled (I am a primary teacher) I started experiencing mood changes, where I felt very irritable and often just colourless or 'blah'. I went off it for a couple of days and my mood improved. I really enjoy fasting and I want to continue but I am wondering if anyone has experienced similar issues. How did you troubleshoot it?