I read a few things about a neurotransmitter within our body called "Serotonin",a high level of Serotonin. makes you have vivid dreams and lucid dreams,they say Serotonin is depleted by REM sleep(and dreams) and naturally restored by dreamless sleep,this might explain for why I never have a lucid after the day I get lucid.

They also mention that a to low level of Serotonin can make you depressed, therefor LDing everyday would make you depressed? Seems unlikely to me.

One person also mentioned he took a 1/4 XTC tab(XTC contains tremendeous amounts of Serotonin) and had like 5 LDs in one night,whoa wonder if thats true..