Children and adolescents require more sleep than adults. The American Academy of Pediatrics (AAP) defines a sufficient night’s sleep for an adolescent as 8.5-9.5 hours per night. But according to data from the national Youth Risk Behavior Survey, just over a quarter of middle and high-school students (27.5%) got 8 hours or more of sleep on the average night in 2015, and most got much less. Researchers have found striking links between insufficient sleep and a range of adverse outcomes in adolescents, including obesity, poor school performance, and behavioral problems including substance use.
For instance, a 2012 longitudinal study of youth (average age 14.7 years) participating in two Minnesota cohort studies found that less sleep—both weekday and total—at baseline was associated with more past-month cigarette and marijuana use 2 years later. A recent analysis of data on eighth graders from the 2010 and 2012 Fairfax County Youth Survey—an annual survey of middle and high school students in one of the largest school systems of the country—clearly showed that shorter sleep duration correlates with higher incidence in several risky behaviors. For example, students who reported getting 6 hours of sleep per night were three times as likely to have initiated drug use than those who got 8 or 9 hours of sleep per night.
Given this striking correlation, it is important to study the neurobiological mechanisms that link insufficient sleep and substance use. Sleep-deprivation–induced impairment of emotion regulation and executive function such as inhibitory control is likely involved. My colleagues and I have found that adults who are sleep deprived show reduced availability (down-regulation) of dopamine D2 receptors in part of the brain’s reward circuit, the ventral striatum. Reduced availability of D2 receptors in the ventral striatum could be expected to increase the risk for behaviors like drug use that produce large surges of dopamine to compensate for this deficit.
We also showed that reduced hours of sleep mediated the low levels of D2 receptors in individuals suffering from cocaine use disorder, which our laboratory and others’ have shown are associated with higher risk for compulsive drug use. Down-regulation of dopamine D2 receptors in the striatum has also been associated with impairment in prefrontal regions necessary for exerting self-control and other executive functions.
The impact of lack of sleep on dopamine receptors suggests that stimulant misuse and impaired sleep could be a vicious cycle: Stimulants impair sleep, and reduced sleep produces changes in the brain that predispose to further drug use and addiction. Two-way interactions between reduced sleep and substance use are also possible with other substances. The Minnesota study, for instance, identified a bidirectional relationship between greater cigarette use and greater weekend oversleep (sleeping late on weekends to compensate for less weekday sleep) and between greater marijuana use and less total sleep.
The mechanisms underlying these relationships are still unknown, but a new longitudinal study in late-elementary schoolchildren found relationships between sleep patterns (reduced total sleep and later bedtimes and wake times on weekends) in 4th grade and cigarette or alcohol use in 6th grade, mediated by sleep-related deficits in inhibitory control.
Further research will be needed to shed more light on the links between sleep and substance use versus non-use. For example, the 10-year longitudinal Adolescent Brain Cognitive Development (ABCD) study, now underway at 20 research sites across the country, will gather data on teens’ sleep patterns as well as substance use and other behaviors and should be able to provide valuable insight into this issue.
From school start times that are too early to the nighttime use of computers and cell phones, today’s adolescents face many challenges to getting a good night’s sleep. The clear links between lack of quality sleep and risk behaviors like substance use make this a crucial target for prevention efforts. Recognizing the many health risks known to be linked to poor or insufficient sleep, the AAP has pressed for later start times (no earlier than 8:30 AM) in middle school and high schools. Parents should be aware of how important it is for their teenage children to get a full night’s sleep every night, as a protective factor against substance use as well as other adverse impacts on their health and success.