Teens' mood swings can be similarly explained by the interplay of physiological and psychological processes associated with maturation. For one thing, many teens have greater fluctuations in neurotransmitters and hormones such as serotonin, GABA and cortisol – all of which can modify their mood. "If you take serotonin, it's the 'feel-good hormone' – and when it's down you're going to get a very low mood," says Coleman.
