Figure 3.

Hierarchical age-period estimates, by sex, of period effects of loneliness among 8th, 10th, and 12th graders in the Monitoring the Future Study (1991–2019), adjusted for self-reported frequency of attaining ≥7 hours of sleep nearly every day or every day. The model also was adjusted for race/ethnicity (non-Hispanic White, non-Hispanic Black, Hispanic, other races or ethnicities), parental education (either parent had some college or less vs. completed college or more, as reported by the adolescent), grade point average (B– or less vs. B or higher), survey implementation technique (paper vs. tablet), and past-year cannabis/alcohol/other drug use. Drugs in the “other substance use” category varied by grade: For 12th graders, we included lysergic acid diethylamide, other hallucinogens, cocaine, amphetamines, sedatives, tranquilizers, heroin, narcotics, crack, and other forms of cocaine. We did not include heroin, narcotics, or sedatives for 8th and 10th graders (girls: n = 120,420; boys: n = 108,926).