i believe it's a slight case of insomnia?

i think i may be suffering from a paranoia of some sort. it seems that i have developed a fear of falling asleep in darkness. this causes me to go to sleep at early hours of the next morning (say 6, 7 o'clock) and wake up at around 1 o'clock in the afternoon. it's causing me to have severe black bags underneath my eyes and strange mood swings. i can be happy one minute then angry the next.
i worry that this isn't just a phase and i need to get it under control before the new school year starts as it's my final year of GCSE and comprehensive so i'd really like to concentrate.

please help. >.<