When you are stressed out, it is especially important to sleep, as without it, you become even more stressed, fatigued, and irritable. The first thing to do is to assess if there is anything you can do to address your stress now and reduce it. If you can't do anything about your stress now, then this gives you permission to just rest and sleep, so that you can better handle the stress at a time when you can do something about it. You may need to take a sleep medication, like melatonin, 3mg tablets. Take one tablet to help you sleep- but if you are not asleep within one hour of taking it, then take two tablets of melatonin. Melatonin is an over the counter medication with minimal side effects.
If you are also so stressed out that you have headaches, then take some ibuprofen to help relieve the pain, and this will also allow you to rest and sleep without the discomfort of the headache.