From Wikipedia: It is well-known that "thinking happy thoughts" can make person feel better, lessen the pain, bring back a good mood, increasing levels of "feel-good" neurotransmitters like dopamine. Even thinking about reward like sex, drugs, alcohol, food, can increase the dopamine levels.[75][76] Researchers found that patients given a placebo released dopamine, just as the brain exposed to an active drug would do.[77] However, some patients are abusing the "thinking happy thoughts" reward system, deliberately invoking happy memories and happy thoughts again and again to naturally produce the "feel-good" neurotransmitters in their brain. This is similar to drug addiction: nearly all drugs, directly or indirectly, target the brain�s reward system by flooding the circuit with dopamine.[78] As a person continues to overstimulating the �reward circuit�, the brain adapts to the overwhelming surges in dopamine by producing less of the neurotransmitter or by reducing the number of receptors in the reward circuit. As a result, chemical�s impact on the reward circuit is lessened, reducing the abuser�s ability to enjoy the things that previously brought pleasure.[78] This decrease compels those addicted to dopamine to increasingly "think deep thoughts" in order to attempt to bring the neurotransmitter level back to normal � an effect known as tolerance. This explains why many of the schizophrenia patients have increased levels of dopamine. Development of the tolerance can eventually lead to profound changes in neurons and brain circuits, with the potential to severely compromise the long-term health of the brain.[79] Modern antipsychotics are designed to block dopamine function. Unfortunately, this blocking can also cause relapses in depression, and can increase addictive behaviors.[80] ========== You better stop thinking pleasant "repetitive thoughts" before it drug you down to schizophrenia