Your heart begins to race.
Your feet sweat and you feel hot and prickly.
Those symptoms of what is an extremely primal fear - the sort nightmares are made of - exacerbate the situation, because part of the alarm you feel is something to do with a loss of control, that your naked body will act in a way you don't fully intend it to.
At the Otago Polytechnic's Dunedin School of Art life drawing night classes, there is a small dressing - or perhaps undressing - room where the model shakily undoes their shoelaces and changes into a gown.
The sudden thought of hitherto secret places being on display hits hard.
But the time has come, the easels stand in a semicircle blocking any escape and it's time to descend a few steps into the room, take your place and drop the gown.
And there you are, ruthlessly exposed under a spotlight, fortunately with not too much time to think about it.
A life drawing class starts off with two-minute warm-up poses, standing with your arms to one side or above your head, your body twisted so the artists have areas of light and shade to work with.
You kneel, you turn your back on the artists, the poses get longer, to five minutes then to 15 in sometimes uncomfortable positions in which muscles cramp and body parts begin to shake unbidden with the exertion.
In short breaks, the model and the artists circle the easels to look at others' work.
And there you are as a series of lines, of dark and shade, filtered by the mind of the artists and the style of their art, their perceptions of you, and you are looking at those perceptions on paper and weighing them up, layering your own vanities on top of them and liking those that paint you in what you see as a good light, and disliking those that make you seem heavy or that highlight areas of your body for some reason you don't like.
After a break on the hour, you start to feel more relaxed.
The second half is an hour-long reclining pose in which you are presented on a velvet blanket of sumptuous purple.
The artists peer round their easels, take a couple of steps back, rest their chin on their hands to contemplate you, then return to their work, scratching and scraping their lines on paper.
And finally, on a strange bed in a strange place, naked and surrounded by staring strangers, you feel completely calm, and sitting still for an hour doing nothing - usually a recipe for the worst sort of ennui - develops into a gentle meditative state.
And then time is up and you're done, and a little like the feeling after public speaking, there is a period of elation having faced such a primal fear and prevailed.
I can - sort of - recommend it.
