Moon is karaka for mind. Thinking process, anger, mental aggression, sorrowfulness, happiness, fear,phobias etc all controlled by Mind, and in turn largely by moon. So overall mental health is decided by Moon.
Moon when aspected by benefics alone will give peace of mind.
The psychological behaviour of a person largely depends on the planet influencing Moon.
Sun conjoing with Moon wii give a lot of anger and temper to the native. Sun aspecting moon will give lot of ego. The degree of anger depends on how close sun is with moon. When a person is very angry, he automatically looses control over mind. That means his mental strength goes minimized. As sun is very close to moon, moon gets combusted and looses his strength. Sun is king in astrology. When Sun aspects moon, moon is near 180 degrees apart from sun, so one feel themselves as king or high ego. Again the position of Moon (in which house he is located) is also important. Again the house owned by Sun as well as Moon are also very important. Sun and Moon connected to 6,8 and 12 cause mental illness.
Mars influencing moon results in perseverance for good if mars is functional benefic or perseverance for bad if mars is functional malefic. Mars gives extreme aggression. If well positioned, the native tends to be military or related fields, and if bad people turn as criminals.
Next, Rahu is very very important. Rahu conjoining with Moon makes people to turn in to extreme behaviors. People even may turn Mad, if there is no other benefice influence and moon has not gained strength. People suffer a lot.
Saturn is less detrimental when conjoins with Moon. Largely people are obedient. If saturn is not good, people may loose self respect.
Jupiter conjoining with Moon, may make people extremely good and honest.
venus influencing Moon make people artistic and creative.
For the people whose strength of Moon is very weak in their respective horoscopes suffer through moon transits. If Moon is good in the horoscope, no need to worry.
During Full Moon day, as Moon is opposite to Sun, people behave with superiority complex. Loose peace of mind due to over ego, may quarrel with everyone.
Again, it depends on he horoscope. Whenever moon conjoins with lord of 8 or 6, people will have mental sufferings.
The best remedy is wear good pearl, as pearl is the stone for Moon.