Does it violate academic social norm to email someone around midnight?
The good thing (maybe the only good thing) about email is that it's by nature asynchronous. A phone call in the middle of the night is intrusive, because there is an explicit expectation that the receiver does something about the call right there and then. An email is not like that - if you send an email, it will happily sit in the inbox of the recipient until they explicitly take an action to react upon it. Consequently, it does not matter when you send the email.
I imagine a scenario where a phone that is linked to gmail rings due to my email, and that wakes up the person I intend to email.
This is, in my opinion, not a valid concern. First of all, the kind of person who is annoyed by getting disturbed by email outside of work hours has a very easy fix to the problem - turn off notifications. In my opinion, if you explicitly have notifications enabled you can't at the same time be annoyed that you get notified.
Second, you'll need to understand an almost universal basic truth - starting from a certain seniority, most people in academia get a lot of email. Hundreds per day, in some cases. Many of these emails will come in during the night. If you wake up every time you get an email from one of your collaborators on a different continent, you won't get much sleep at all. So your email is highly unlikely to wake anybody up, because it will drown in the flood of other emails people get over the night.
That said, as discussed in a somewhat related recent question, if you are a supervisor or manager, it may pay to be somewhat careful about what "message" you transport with when you send emails. In this question, a student was stressed because their supervisor kept sending them mails in the night, and the student interpreted these as work items that needed to be done by the next morning. Also, if you as a supervisor are clearly working until midnight, it may implicitly communicate certain expectations and standards that you don't really want in your team.
No, you do not have to refrain from doing this.
What is midnight to you? Is it now? Because if it's midnight for you now, halfway across the world, it's noon. It's completely logical that someone halfway around the world will be active right now. If this person wants to email you, should he or she wait 12 hours until it's noon for you?
If anything, I'd say you (or the person you're emailing) should turn off your phone when going to sleep.
People have different wake/sleep and work/relax rhythms, and with flexible working hours and home office, it's hard to guess when people do work and when not (especially in academics).
Therefore I think the responsibility shifted from the sender to the receiver of the message: Most (all?) smartphones nowadays have a "do not disturb" modus which automatically turns off the sound and vibration at night or during personally defined times. Send me e-mails whenever you want or call me whenever you want, because if I don't want to be disturbed, I take care I won't.