You could be suffering from Sleep apnea which is a common disorder but it can be serious also.
Some of the symptoms of sleep apnea are snoring (usually noticed by others!), day time sleepiness, fatigue, headaches etc.
The causes of sleep apnea can be being overweight, airway abnormalities, medications, central cause (neurological) etc.
Sleep apnea can lead to cardiac and neurological complications and hence it is important to get yourself evaluated by your doctor for the causes so that treatment can be started right away.
In the meanwhile, you can try some of the following: improving your sleeping environment, avoiding stress, having a healthy diet.
Do write in if you need more information.