Setting parental controls for my impulsive self?

Due to a neurological disability, I have impulsivity issues at night (when my behavioral medication has worn off) and am prone to staying up too late on the computer. This normally would be a simple matter for parental controls, but since I am in my 20s, I basically need to have access to the admin account to install/uninstall programs, do system maintanence, etc. but if I have memorized the password, I will simply wind up disabling the parental controls at night. I have tried making it a complex, hard-to-memorize password that is stored in really awkward places I'd only access if I'm really determined (ie, not at night when I can't be bothered) but sooner or later, I memorize these passwords, and I am memorizing them faster and faster.

What would be ideal is a multi-level admin system in which most administrator functions could be accessed via one password, but the parental control time limit could only be accessed via another, super-complex password that I'd never memorize. However, as far as I can tell, this is not the case, so I am not sure what I can do for a long-term solution. (If there is a way, please, please let me know.)

Any thoughts or ideas? Yes, I need the computer for my classes, again owing to other effects of my disability. No, I can't solve this with more "self control." I've tried "self control" at night for over a year to no avail.

Sigh. I was hoping to avoid that, but I may have no choice...

Thanks

What would be the goal of the control? To prevent internet access? To prevent ANY usage? Prevent particular programs from running?

Preventing any usage would be ideal, but preventing individual programs or even just internet access would be helpful.

There are serious problems for all those requirements. Basically, if you need admin permissions, you will always be able to remove whatever protections you may place upon yourself. There is no such things as a "multi-level" admin permissions, you either have FULL access to everything, or just to your private files (and any OS has a similar situation, not just Windows). Some portion of self-control is absolutely necesary if you want to keep your admin password, otherwise you'll need someone else to keep admin permissions away from you.

If you want to completely prevent usage in certains hours, the best I can think of is to use an auto-shutdown procedure.
Use Task Scheduler to execute a task regularly during the "no usage" period that simply shuts down the system. If you attempt to use the computer, it will just power itself off as soon as it boots, with no chance for you to do anything.
Does it need to prevent to power on the system, or should it abruptly in midnight?

Thanks for all the help and ideas. The auto-shutdown seems a little bit extreme, but I am keeping it in mind.

Giving the admin password to someone else currently looks like the most likely option. Actually, the fear of having to do that actually has had a restraining effect on me when I am off my meds.