Hi - I used to run a team of homeworkers, so could I give some advice?
Are you ill? If so, follow your employer's usual procedure for reporting that you're sick. (Usually a person-to-person call is required between employee/manager).
If your manager is not on duty, send an email, and put an answer-machine message on your phone asking callers to leave their number, and you or a colleague will respond to their call in the morning.
If you have a colleague you can ask to cover you tonight, do so.
In the morning, call your boss first thing, explain you were not well, and tell him/her what you did to contain the situation.
If you're just tired, I'd actually recommend you soldier on - you'd probably have to if you were in the office, after all.
The thing about homeworking is that you really have to show your boss that you can self-manage - which means that you HAVE to be able to make sure that the business suffers as little as possible during an emergency (such as illness).
Sounds like there might not be any laid-down procedures. Why not suggest something to your boss in case someone else has similar problems in future? Be proactive!
Hope you're feeling better tomorrow after you've got some rest.