Sleep disturbance refers to disruptions in normal sleep quality, duration, timing, or continuity and is associated with altered circadian rhythm regulation, neurotransmitter imbalance, inflammatory signaling, oxidative stress, hormonal disruption, and metabolic dysregulation. Research has linked inadequate sleep and circadian instability to impaired glucose metabolism, elevated cortisol signaling, increased oxidative stress, altered melatonin production, inflammatory pathway activation, endothelial dysfunction, and changes in neurochemical regulation involving serotonin, dopamine, and norepinephrine pathways. Sleep quality is closely connected to circadian rhythm synchronization, light exposure, meal timing, stress signaling, hydration status, micronutrient intake, and nervous system balance. Whole-food plant-based dietary patterns emphasizing magnesium-rich vegetables, antioxidant-rich fruits, fiber, complex carbohydrates, and polyphenol-rich foods may support circadian alignment and neurotransmitter stability. Plant foods containing tryptophan, magnesium, potassium, flavonoids, and antioxidant phytochemicals may help support melatonin synthesis, autonomic balance, endothelial function, and nervous system recovery. Diets high in refined sugar, ultra-processed foods, added oils, alcohol, excess sodium, and stimulatory additives have been associated with circadian disruption, increased inflammatory burden, and impaired sleep quality. Fiber-rich diets may also influence sleep quality through gut microbiome signaling and SCFA production. Circadian regulation involves interactions between stress-response pathways, cortisol rhythm stability, melatonin signaling, glucose metabolism, mitochondrial function, and neurotransmitter turnover. Research involving green tea compounds, berries, cruciferous vegetables, herbs, leafy greens, legumes, and whole grains demonstrates associations with antioxidant defense, inflammatory modulation, vascular support, and neuronal protection. Stable blood sugar regulation, hydration balance, and anti-inflammatory plant nutrition patterns may contribute to improved nighttime recovery and daytime cognitive resilience.