Doctors Answers (2)
Going to sleep at 3 AM and sleeping until noon is what is called a delayed phase sleep syndrome. It is normal in the teenage years, but in adulthood it generally goes away due to the need to adapt to the rest of the world. Sometimes, if there is no reason to change, it will continue. Changing to usual sleep-wake times may require a combination of medication, work on your part and appropriate exposure to light. A sleep specialist can help with this plan.
If you do not have an actual sleep disorder than most likely the problem revolves around your sleep hygiene. In order to move your bedtime up you should start by going to bed earlier in 30 minute increments. When you go to bed 30 minutes earlier, you should get up at your desired wake time. That being said, you will not be getting as much sleep as you normally do, however if you persist in this plan you should be able to change you sleep schedule.