The suprachiasmatic nucleus of the hypothalamus is the master circadian pacemaker that synchronizes peripheral clocks and regulates melatonin secretion, cortisol rhythmicity, and monoamine neurotransmitter cycling — disruption of SCN-mediated circadian rhythms destabilizes mood regulatory systems, and individuals with bipolar disorder have intrinsic circadian clock gene polymorphisms that increase vulnerability to rhythm disruption

Circadian rhythms are purely behavioral habits with no neurobiological substrate; shift work triggers mania through psychological stress alone, not through any disruption of biological clock mechanisms

Melatonin is the sole neurotransmitter involved in mood regulation, and circadian disruption causes mania exclusively through melatonin depletion without affecting any other neurochemical system

Circadian rhythm disruption only causes depression, never mania; this patient's manic episode must be coincidental to his schedule change and entirely unrelated to circadian factors