I also have had chronic problems with being overly tired. I see neurologists and right off the bat they tested me for sleep disorders. It turned out I had sleep apnea (a very common problem that can be very dangerous) and they recommended either CPAP or surgery (I had the later). Sleep apnea will rob you of deep stage sleep and constantly wake you up, thus making you tired throughout the day. Also, anxiety is notorious for disrupting sleep. And, as you have already discovered, it's very important to have a sleeping routine/schedule. This can have a dramatic effect on acquiring deep and meaningful sleep.

There are myriad other conditions that can result in being overly tired such as depression, anxiety, sleep apnea, narcolepsy, alcoholism or drug abuse, chronic fatigue syndrome, fibromyalgia, chronic pain syndromes etc. I would strongly recommend seeing a medical doctor as a precautionary measure.

JeffreyREBT