The Impact of School Start Times on Adolescent Health and Academic Performance

“The combined evidence from clinical and epidemiological studies leads to a reasonable hypothesis that sleep deprivation or disturbances are associated with increased risk for adolescent suicidal behavior.” ⁽¹²⁴⁾—Xianchen Liu, M.D., Ph.D., former Assistant Professor of Psychiatry, University of Pittsburgh, Daniel Buysse, M.D., Professor of Psychiatry and Clinical and Translational Science, University of Pittsburgh.

The majority of children who attempt or contemplate suicide are likely to suffer from depression. ^{(380, 391, 392)} Depressed adolescents suffer from heavily increased incidence of nightmares compared with healthy peers. ⁽²²¹⁾ Adolescents who experience frequent nightmares and sleep less than 8 hours a night have been shown to be at higher risk for suicidal behavior. ⁽¹²⁰⁾

Sleep loss or disturbances may signal an increased risk of future suicidal action in adolescents. ^{(120, 121, 122, 123, 124)} A 2011 study published in the Journal of Psychiatric Research found that children who had trouble sleeping at 12 to 14 years of age were more than twice as likely to have suicidal thoughts at ages 15 to 17. ^{(400, 401)}

The association between short sleep duration and suicidality has been hypothesized to be due, in part, to the “negative effects of insufficient sleep on judgment, concentration, and impulse control.” ⁽¹²¹⁾ Sleep problems and sleep deficiency have long been associated with suicidal ideation in teens. ^{(52, 53, 400)}

Poor academic performance can be among the risk factors for teen suicidality. ^{(391, 402)} As previously noted (see, §§ III, III.A., supra), sleep deficiency and early school schedules have been closely associated with diminished academic achievement. ^{(2, 13, 24, 27, 29, 30, 34, 35, 44, 45, 49)}

The incidence of suicide begins to increase rapidly during adolescence. ⁽⁴⁰⁴⁾ Among U.S. adolescents, suicide is the third leading cause of death, in recent years accounting for 10% or more of all teen fatalities. ^{(405, 406)} Recent data put the suicide rate in the general U.S. population at 2.7%. ⁽⁴⁰⁷⁾

When advised in June of 2011 that St. Paul Public Schools intended to advance middle and high school fall start times by up to an hour to 7:30 a.m. in order to save busing expenses, Conrad Iber, M.D., Professor of Medicine and Sleep Medicine Director of the Minnesota Medical Center, cautioned that the resulting sleep loss “will affect those particularly vulnerable. … ‘There’s an increased risk of suicide.’ ” ⁽⁴⁰³⁾ 

In a 2014 study aptly entitled, “Sleepless in Fairfax: The Difference One More Hour of Sleep Can Make for Teen Hopelessness, Suicidal Ideation, and Substance Use[,]” scientists examined weekday reported sleep duration and its relationship to depression, suicidality, and substance use in a large and ethnically diverse sample of 27,939 8th, 10th, and 12th grade students in the Fairfax County Public Schools system, the 13th largest in the country. ^(250.1) Utilizing data from the 2009 Fairfax County Youth Survey, researchers found that substance use for tobacco, alcohol, marijuana, and illicit/prescription substances increased steadily as students obtained less sleep. ^(250.1; see also, § III.G., infra.) Notably, in 2009, Fairfax County high schools began at 7:20 a.m., ^(250.1) and middle schools between 7:25 a.m. and 8:05 a.m. (See, Appen. A, infra, Schools Recently Delaying Start Times, etc.) For each hour less sleep obtained, the odds of youths feeling sad and hopeless increased by 38%, of reporting serious suicidal ideation, by 42%, and of having already attempted suicide increased by a “striking 58%.” ^(250.1) The scientists conclude the odds of feeling sad and hopeless “accumulate multiplicatively with each hour of sleep lost such that for a student receiving three less hours of sleep (e.g., 5 h/night – compared to a student receiving 8 h) the beta coefficient would be multiplied by 3, yielding odds ratios of 2.64, 2.85, and 3.92 respectively,” making such a youth more than 2.5 to almost 4 times more likely to be depressed and/or suicidal. ^(250.1)

A recent study of 8,010 Korean students in grades 7-11 investigated the association between suicidality and behaviorally induced insufficient sleep syndrome (BISS), the most commonly suggested cause of short sleep duration among adolescents. ⁽⁴⁰⁴⁾ The researchers, all four credentialed as both physician (M.D.) and Doctor of Philosophy (Ph.D.), defined BISS as satisfying all of the following criteria: (1) a short sleep duration on weekdays (≤ 7 hr); (2) a long weekend oversleep (≥ 2 hr); (3) severe daytime sleepiness (Epworth Sleepiness Scale ≥ 9); and, (4) the absence of significant insomnia. ⁽⁴⁰⁴⁾ “Korea provides an exceptional opportunity for investigations of BISS in adolescents[]” because Korean adolescents have been “shown to have shorter sleep durations and longer weekend oversleeps, as compared with their peers in other countries.” ⁽⁴⁰⁴⁾

Korean middle and high schools begin between approximately 7 a.m. and 8:30 a.m., releasing students between 4 p.m. and 6:30 p.m. ⁽⁴⁰⁴⁾ Thereafter, “almost all” Korean adolescents attend private educational institutions or go to night school, generally concluding between 9 p.m. and midnight. ⁽⁴⁰⁴⁾ Korean adolescents are under “strong socio-cultural/familial/psychologic pressure to perform well on their college entrance examinations, many of them respond by sacrificing sleep and studying for longer periods of time.” ⁽⁴⁰⁴⁾

In this 8,010 student sample, 6 hours, 3 minutes represented the average weekday sleep duration, 8 hours, 41 minutes the average weekend sleep duration. ⁽⁴⁰⁴⁾ One thousand five hundred four (1,504) or 18.78% of the study participants were classified as having BISS. Five thousand seven hundred forty-three (5,743) or 71.70% without BISS or significant insomnia were classified as not having BISS. ⁽⁴⁰⁴⁾ Subjects without BISS, 2,031 (25.51%) who slept ≥ 7 hr on weekdays were defined as “subjects with sufficient sleep.” ⁽⁴⁰⁴⁾ (As noted above (see, § II.A., supra), the National Sleep Foundation defines sleep as insufficient if <8 hours per night, borderline if 8 hours per night, and optimal if >9 hours per night.) ⁽²⁶⁾

Subjects with BISS were found to have higher Beck Depression Inventory (BDI) and Beck Scale for Suicidal Ideation (SSI) scores than subjects without BISS or subjects with sufficient sleep (all P < 0.001). ⁽⁴⁰⁴⁾ Even after controlling for BDI scores, subjects with BISS had significantly higher SSI scores than subjects without BISS (F = 7.84, P < 0.01) or subjects with sufficient sleep (F = 11.71, P < 0.001). ⁽⁴⁰⁴⁾ As hypothesized, subjects with BISS slept less on weekdays and more on weekends, overslept longer on weekends, and had a larger weekend rise time delay and a higher ESS score than subjects without BISS or subjects with sufficient sleep (all P < 0.001). ⁽⁴⁰⁴⁾

In the absence of evidence shedding light on the “causal pathway linking chronic sleep deprivation to suicidality[,]” the researchers surmised as “plausible that chronic sleep deprivation in adolescents might increase suicidality through heightened impulsivity or intolerance to other stressors. In addition, the neurobiologic effects of chronic sleep deprivation may be related and increase suicidality.” ⁽⁴⁰⁴⁾

Weekend rise time but not weekend bedtime was found to be delayed. ⁽⁴⁰⁴⁾ Eveningness was found to be related with daytime sleepiness, longer weekend oversleep, and BISS. ⁽⁴⁰⁴⁾ Like their colleagues in the United Statees, ⁽⁴¹⁾ the Korean scientists recognize the merits of later school scheduling in addressing adolescent sleep deprivation and suicidality. ⁽⁴⁰⁴⁾

“These findings suggest that adolescent sleep insufficiency might be caused by a mismatch between intrinsic factors such as circadian rhythm and extrinsic factors such as school schedule. Furthermore, the current study suggests that sleep insufficiency induced by this mismatch might mediate the relationship between eveningness and suicidality /depression, and modifying school start times may reduce sleep insufficiency and associated suicide risk. ^(404, citations omitted.) [¶]

  “In conclusion, we found that BISS among Korean adolescents is associated with increased suicidality. In addition, chronic sleep deprivation, as represented by weekend oversleep, was found to be associated with suicidality independently of depression, insomnia, snoring, and daytime sleepiness. Accordingly, our findings suggest that chronic sleep restriction among adolescents may independently increase suicide risk.” ⁽⁴⁰⁴⁾

Perhaps ironically, a recent study of 4,553 Korean middle and high school students (grades 7-10) suggests that weekend catch-up sleep (as an indicator of insufficient weekday sleep) is significantly associated with suicidality in this population. ⁽⁴⁰⁸⁾ In addition, higher scores on the Beck Depression Inventory, longer weekend catch-up sleep, longer time spent in private educational institutions, and poor academic achievement, were associated with suicide attempts and self-injury. ⁽⁴⁰⁸⁾

In discussing treatment strategies to address serious consideration of suicide and other health-risk behaviors associated with sleep deprivation among adolescents, ⁽⁵³⁾ CDC scientist Lela McKnight-Eily, Ph.D., advised, “Public health intervention is greatly needed, and the consideration of delayed school start times may hold promise as one effective step in a comprehensive approach to address this problem.” ⁽⁵²⁾