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 can also be classified based on the underlying reasons for insomnia such as sleep hygiene, medical conditions, sleep disorders, stress factors, and so on. It is important to make a distinction between insomnia and other similar terminology; short duration sleep and sleep deprivation.