While it’s true that insomnia can and usually is caused by a psychological issue, it can be that you are in perfect psychological condition and still experience insomnia
This happens to a lot of people that regularly spend a lot of time in front of the computer
That’s because monitors emit blue light
That prevents you from experiencing a quality sleep.
If you want to solve this you can download Iris, which is a program that can reduce the blue light that your monitor emits
You can also see more info about Blue Light here:
How Blue light Destroyed our Sleep? – Iris – Software for Eye protection, Health and Productivity