I really dislike how often the word "insomnia" gets banded about. One restless night isn't insomnia in the same way that one tickly chest cough isn't Bubonic Plague.
As above. Stay awake now until the evening. Have a shower to wake yourself up, perhaps walk instead of drive, avoid comfy chairs or warm, cozy environments. Then, come 10pm, you'll be ready to pass out.
If you really do have actual insomnia and you're still unable to sleep for a few days, i'd recommend a doctor. I'd also recommend it in the case of Bubonic Plague.