Sleep has been identified as playing a critical role in enhancing memory and improving physical functions. As a central nervous system stimulant, caffeine functions as an adenosine antagonist, impacting sleep. Similarly, nicotine disrupts sleep by affecting neurotransmitters involved in sleep regulation. This study aims to examine the bidirectional relationship between sleep problems and caffeine and nicotine consumption using large longitudinal data representative of the U.S. population and employing a fixed-effects model. I found that households with sleep problems consistently showed a higher rate and larger volumes of caffeinated products and cigarette purchases compared to those without sleep problems. This pattern was even more pronounced in cigarette purchases. Regression analysis demonstrated a bidirectional relationship between sleep problems and the purchase of caffeinated products and cigarettes. However, when household fixed effects were included, the relationship between sleep problems and caffeine product purchases was no longer insignificant, whereas the association with cigarette purchases remained robust.
