Sleep: a neglected public health issue

Controlled by circadian rhythms and sleep–wake homeostasis, sleep is a state of reduced mental and physical activity—a time for body and mind to recharge in preparation for the next day. Although adults aged 18 years and older are recommended to get 7–9 h of sleep per day (and children up to 12 h), the 24/7 economy, modern lifestyles, job stresses, and living environments adversely affect the timing, duration, and quality of sleep for many people.