I work night shift and come back home around 1am. I try to be in bed by 2am but I'm having difficulty sleeping through the night. I just cannot sleep. I have various thoughts flooding my mind and have rapid heartbeats. But I fall very sleepy during the next day afternoon especially after lunch and sleep for few hours till it's time to go to office. I feel sleepy even in the office and unable to focus at work. Do I have insomnia? If so, which type of doctor/specialist to consult?