Im falling asleep at random times in the day... much more often now than ever be!

Im falling asleep at random times in the day... much more often now than ever before. What should I do?

My diet is quite unhealthy, but I have never gained much weight.
It's been happening all my life, but recently it has been more noticeable.
My sleep patterns are often disturbed by episodes of insomnia... Furthermore, I will sleep for well over 12 hours, sometimes straight through several alarms, including my mother, who told me I talked to her. I have no recollections of any of them.
Other times I might be too scared to sleep as I also get quite paranoid over little noises. I keep the fan, or computer on in my room to prevent me from hearing them.

I have just gone through my last year of 6th form, which my school attendance and grades suffered due to the amount of sleep problems that crop up in very random orders.

What should I do?

I would suggest getting a medical checkup. Thyroid problems especially being too low could cause this, or blood sugar variations. Other hormones could also be related, or allergic disorders. Even mood disorders like bipolar problems with manic depressive swings could be related. With your realization that your diet is not healthy, you probably have a big part of the problem. A regular diet with enough protein for longer lasting energy instead of sweets or carbohydrates that give quick highs and quick lows. Fats tend to make you sleepy. Regular exercise is also important not just for weight control, but as part of a routine that takes care of your body. Sleep hygiene is important. Perhaps the computer in your room is not a good idea though the noise of it to mask other noises is a good idea. See my response to someone else with sleeping problems so I don't need to repeat. Interestingly enough, zero point theory of archeology thinks that the vibration of the universe is changing, so sleep disturbances are more common, as our heart rate as our basic rhythm are getting out of tune, as the planet is getting ready to flip the North and South Pole. This means it is even more important to try to get a regular schedule to help your sleep. Our continuous light exposure is also detrimental to our sleep, so hopefully your room can be darkened enough. Otherwise some people are just very deep sleepers so that it is almost sleep walking/talking. Medication may be needed to help you regulate your life after you have been investigated by your doctor. Anti-depressants are non-addicting sleep aids that may help you to get your life more under your own control. If there is trauma in the past it may be helpful to take some counseling or to learn self-hypnosis so you can get restful sleep again when you want to. You only have one body so be good to it with proper food and exercise so it can be good to you. Good luck. Maybe this summer is a good time to get good habits to help yourself after other things have been ruled out.