Recent studies in neuroscience have indicated that as people fall in love, the brain consistently releases a certain set of chemicals, including the neurotransmitter hormones, dopamine, norepinephrine, and serotonin, the same compounds released by amphetamine, stimulating the brain's pleasure center and leading to side effects such as increased heart rate, loss of appetite and sleep, and an intense feeling of excitement.
Research has indicated that this stage generally lasts from one and a half to three years.
If sexual passion is also involved, then this feeling is called paraphilia.
A common principle that people say they love is life itself.
Love encompasses a variety of different emotional and mental states, typically strongly and positively experienced, ranging from the deepest interpersonal affection to the simplest pleasure.
An example of this range of meanings is that the love of a mother differs from the love of a spouse differs from the love of food.
(Further possible ambiguities come with usages "girlfriend", "boyfriend", "just good friends").Throughout history, philosophy and religion have done the most speculation on the phenomenon of love.In the 20th century, the science of psychology has written a great deal on the subject.Most commonly, love refers to a feeling of strong attraction and personal attachment.Ancient Greek philosophers identified four forms of love: essentially, familial love (in Greek, storge), friendly love (philia), romantic love (eros), and divine love (agape).