Full moon is a lunar phase that occurs when the Moon is on the opposite side of the Earth from the Sun. More precisely, a full moon occurs when the geocentric apparent (ecliptic) longitudes of the Sun and Moon differ by 180 degrees; the Moon is then in opposition with the Sun.^[1] As seen from Earth, the hemisphere of the Moon that is facing the earth (the near side) is almost fully illuminated by the Sun and appears round. Only during a full moon is the opposite hemisphere of the Moon, which is not visible from Earth (the far side), completely unilluminated. Many disorders seem to follow the phases of the moon. Epilepsy and headaches often follow this cycle. Some people don’t sleep on the night of the full moon. Scientists have proved that the phases of the moon really have an effect on the mind.

Actually, the Moon has influenced life and the mind of people since the beginning of time. The cave men believed that the Moon was a God. They picture it in many cave drawings. Down through the ages and even today many cultures and religions worship the Moon. The heathen religion, for example, is very Moon Oriented.

The Moon controls the ebb and flow of liquids, be it fleshly fluids or the powerful flood of the ocean tides. Many calendars and almanacs include Moon Phase Planting Guides and even Fishing Guides.

Everybody knows such expression as “mood madness”, in fact, it close to the truth. The word “lunatic” is descended from the Latin word “luna” that means moon. You may not believe that the moon can cause a person to go mad, but the full moon seems to have an effect on emotional condition. It has been noticed that cell block fights, riots and general contention among inmates increase in the periods of full moon.

That’s why scientists advise to keep a close watch on the prisoners, and suggest the policemen to be more alert than usual during the time of full moon. There may a few “loonies” wandering the streets.

Animals are also influenced by the moon. One study repots that animals are twice as likely to bite people during the time of full moon.  Take to your consideration the creatures of legends and myths. Thus werewolves need the light of the full moon to display the change, and vampires walk the night beneath the light of the moon.

All these facts confirm that it should come as no surprise that, when the moon is full, some people may suffer from insomnia, nightmares, strange dreams, and some people even sleepwalk. There is one more interesting fact that some people sleep better when the moon is full, even if its shine falls into their faces.

(source: http://en.wikipedia.org/wiki/Full_moon and http://www.insomnia911.com/sleep-insomnia/moon.htm)