Hello, there.

[1] Regular coffee drinkers are keeping their bodies on a constant state of emergency.

Couldn't the on be, or shouldn't it be, in --- in a constant state of emergency?

Hiro/ Sendai, Japan

P.S. I'm reading an article on allergy to caffeine because I am allergic to it, and so are surprisingly many.
Yes it should be in a constant state of emergency.

You might use 'on' in some contexts though - coffee drinkers are keeping their bodies on a high.
Students: Are you brave enough to let our tutors analyse your pronunciation?
Hi, Nona. How are you? Fine, I hope!

The paragraph is like the following. Could you confirm in is still the right preposition to use here. Thanks, Nona.

Hiro/ Sendai, Japan

Caffeine not only blocks the action of adenosine, it also stimulates the adrenal glands to produce two stress hormones - adrenalin and cortisol. This gives a small kick to the system and, as part of the enjoyment of an occasional capuccino, is no bad thing. But regular coffee drinkers are keeping their bodies on a constant state of emergency by stimulating themselves with caffeine. Imagine that your adrenal glands are like a bank account. Genetic factors and your lifestyle determine how long you can continue to make repeated withdrawals against your energy reserves and still maintain good health. If you are one of those coffee drinkers who think that they get no effect from caffeine, you need to think again. If you can go to sleep right after a double shot of espresso, ask yourself why your adrenal glands have stopped responding and what that says about your adrenal health.
I think it should be 'in'