I am also experiencing similar pain. I am 19 weeks pregnant and my belly button and the area right around my belly button hurt from time to time. It is sometimes constant but other days doesn't hurt much at all. I have been experiencing this for a couple weeks now.
The immune system is intricately connected to the hormonal system and the brain via messenger molecules, so that emotional stress and factors like insomnia have a great influence on its ability to function properly.
Insomnia is both a disorder and a common symptom of many other sleep disorders like sleep apnea or snoring. Sometimes a person with insomnia is experiencing insomnia as a secondary issue and should address the primary cause of their inability to sleep.