Delayed Sleep Timing in Teens Study

Mounting evidence indicates that delayed sleep phase (DSP) may confer risk for adolescent
substance use (SU) and SUDs. However, the exact nature of this link and the mechanisms
underlying it remain unclear. Circadian misalignment, a mismatch between late sleep hours and
early school start times, is a compelling potential contributor to elevated SU in adolescent
DSP with plausible neurobehavioral mechanisms. The investigators hypothesize that
DSP-associated circadian misalignment decreases impulse control and increases reward
sensitivity, thereby increasing SUD risk.

This study will, for the first time, (1) comprehensively characterize the SUD risk profile
associated with adolescent DSP, and (2) probe whether SUD risk is diminished by altering
sleep/circadian timing. The study will assess both established markers of SUD risk and
putative neurobehavioral mechanisms (impulsivity and reward sensitivity). Specifically, the
investigators will employ a comprehensive, multi-method approach to examining DSP's role in
SUD risk, combining laboratory, experimental, and longitudinal studies. The investigators
will recruit a sample of 150 eleventh and twelfth graders (16-19 y/o), divided between 100
DSP and 50 normal phase teens. The investigators will focus on cannabis and alcohol use given
their prevalent use in adolescents and evident links to DSP.

In the experimental study, the investigators will probe whether stabilizing circadian phase
in the DSP group (n=100) by using sleep scheduling and chronotherapeutic approaches (i.e.,
dim light in the evening and bright light in the morning) improves sleep and neurobehavioral
function relevant to SUD risk.

Inclusion Criteria:

- Age 16-19 years

- Currently in 11th or 12th grade and enrolled in a traditional high-school (not cyber-
or home-schooled)

- Physically and psychiatrically healthy, as determined by instruments described below

- Provision of written informed consent and assent Additional inclusion criterion for
Experimental protocol

- Meets operational definition of delayed sleep phase (DSP; weekend bedtime ≥1 AM)

Exclusion Criteria:

- Significant or unstable acute or chronic medical conditions

- Past or current bipolar disorder or psychotic disorder

- Past or current substance use disorder other than alcohol use disorder or cannabis use
disorder

- Past month recreational drug use other than alcohol, cannabis, and nicotine

- Current syndromal sleep disorders other than insomnia and delayed sleep phase disorder

- Medications that interfere with sleep and/or reward function (antidepressants, and
stimulants prescribed for ADHD are permitted)

- Conditions that would interfere with the MRI procedures (e.g., non-removal
ferromagnetic devices)