How do you overcome social anxiety/choking during interviews?

  "Adding manpower to a late project makes it later" - Fred Brooks.

  "5 minutes when alone is worth 15 when being watched" - Me, at 3am

  "Even the Eiffel tower looked ugly during construction" - Also Me, at 4am

A technical interview seems like an artificially constrained setting which is rarely seen IRL.

1. Interviewer already knows the answer. 2. Interviewer has no time constraints. 3. Interviewer is not judged when he 'thinks out loud'. 4. Interviewer has no repercussions.

In contrast:

1. Candidate does not know the answer. 2. Candidate has 30 minutes. 3. Candidate is judged on his 'approach'. 4. Candidate's job status is at stake.

I find it hard to think freely under these constraints.

If I am judged on my approach, I have to be slow/cautious in what I speak, and ignore the time constraint.

If I am judged on my result, I have to be fast/random in my thoughts, and ignore the approach constraint.

If I am judged on both, I have to change into pyjamas, put my feet up on the table, gesture wildly with my arms, and ignore the 'human being in front of me' constraint.

I would love to know whether that particular interviewer solved that particular problem when they encountered it for the first time ever, within 30 minutes, while being watched and judged on both their approach and the result.

If not, I would love to ask if they (or I) could leave the room and come back after 15 minutes. Is this feasible ?