#insomnia

I have been waking up every night the past week around 4am and can't get back to sleep usually until 6am. It's annoying when I have to work the next day. I picked up this bad habit when I got pregnant with my son about 5 years ago and have not been able to shake it off. I would go for weeks without the insomnia but then it would come back. I don't know what is triggering it: stress, exercise or lack thereof, diet, work, ...? I have no idea.