I use the PowerShell ISE in a lot of dimly lit places and it can be a bit disconcerting to have a very bright computer screen to look at when you are in a dark room.
The default ISE shell supports themes. You can chance to a dark theme from
Which will change the UI to this:
You can also import themes from the Manage Themes dialog box. Here is a nice one I found on GitHub https://github.com/perplexityjeff/PowerShell-ISE-Solarized-Theme