The phrase out of one's head works as an adjective to describe someone acting irrationally.

The HEA exhibited exceptional strength at high temperatures.

After all their struggles, they lived HEA.

After attending the HEA workshop, she revised her teaching portfolio to meet the new standards.

To lead the team effectively, one needs to have one's head screwed on straight.

One needs to have one's head screwed on right to handle this job.

If anyone betrayed the king, the royal guard would give someone his head on a platter without hesitation.

Anyone who wants to be heard should put a civil tongue in one's head and choose words carefully.

After working at the computer all day, I felt headachey and needed to lie down.

When facing unexpected challenges, one must keep one's head on one's shoulders to make rational decisions.