The interplay between sleep quality and anxiety in adults has garnered significant attention in psychological and medical research, given the profound implications for mental health and overall well-being. This comprehensive review aims to elucidate the intricate relationship between these two constructs by analyzing current literature, integrating results from observational studies, randomized controlled trials, and meta-analyses. Poor sleep quality is often characterized by difficulties in initiating and maintaining sleep, reduced sleep duration, and non-restorative sleep. Such disturbances have been shown to exacerbate anxiety symptoms, contributing to a cyclical pattern where anxiety itself further impacts sleep quality. The review highlights various mechanisms underlying this relationship, including hyperarousal, rumination, and dysregulation of neurobiological pathways, such as the hypothalamic-pituitary-adrenal (HPA) axis. Numerous studies indicate that individuals with anxiety disorders report significantly lower sleep quality compared to their non-anxious counterparts. Specific anxiety disorders, such as generalized anxiety disorder and panic disorder, have been identified as particularly associated with sleep disturbances. Interventions targeting sleep, including cognitive-behavioral therapy for insomnia (CBT-I) and pharmacological treatments, are discussed in relation to their efficacy in alleviating anxiety symptoms and enhancing sleep quality. Moreover, the review addresses the potential bidirectional nature of the relationship, suggesting that not only can poor sleep contribute to increased anxiety, but anxiety may also lead to long-term alterations in sleep patterns. Implications for clinical practice are presented, emphasizing the importance of comprehensive assessments that incorporate both sleep and anxiety evaluations. Finally, the review identifies gaps in the existing literature and suggests directions for future research, including the need for longitudinal studies and investigations into the biological underpinnings of this relationship. By synthesizing current findings, this review contributes to a deeper understanding of the association between sleep quality and anxiety, aiming to inform effective interventions and promote better health outcomes in adults.