A new study of undergraduate students found that individuals with attention-deficit/hyperactivity (ADHD) disorder were more likely to be evening types compared to individuals without this disorder. Furthermore, individuals with ADHD were more prone to exhibit depressive symptoms. This trend was especially pronounced among evening-type participants. The study was published in the Journal of Sleep Research.
Circadian rhythms are natural, internal biological processes that follow a roughly 24-hour cycle. These rhythms regulate various physiological and behavioral patterns in living organisms, including the sleep-wake cycle, hormone production, and body temperature.
There are two prevalent circadian preferences: morning and evening types. Morning types often feel more alert and energetic during the early hours and tend to wake up naturally, whereas evening types gravitate towards staying up later, feeling more lively and active in the latter part of the day. An individual’s genetic composition influences these preferences, which can subsequently affect their daily routines and efficiency.
There is mounting evidence that individuals with ADHD tend to more often be evening types. Attention-deficit/hyperactivity disorder is a neurodevelopmental disorder characterized by persistent patterns of inattention, hyperactivity, and impulsivity. It usually starts at an early age but can also continue into adulthood.
Study author Stephen P. Becker and his colleagues wanted to test this by examining the associations with ADHD symptoms and circadian rhythms. More precisely, they wanted to know whether ADHD symptoms of inattention and hyperactivity-impulsivity are associated with specific circadian preferences, but also whether this association is linked to some other psychopathological symptoms.
The study encompassed 4,751 undergraduate students from five universities across various US regions. Of these, 73% were female, and 80% identified as white. Half were in their first year of college.
Participants underwent evaluations of circadian preference using the Morningness – Eveningness Questionnaire (MEQ). They were also assessed for ADHD symptoms through the Barkley Adult ADHD Rating Scale-IV (BAARS-IV) and for depressive and anxiety symptoms using the Depression Anxiety Stress Scale-21 (DASS-21).
The data revealed that approximately 14% of participants exhibited heightened ADHD symptoms. Within this group, 45.6% primarily displayed inattention symptoms, 32.8% were chiefly hyperactive-impulsive, and 21.6% exhibited a mix of ADHD symptoms. Additionally, 30% of participants were evening types, 7% morning types, with the rest falling somewhere in between.
Participants with ADHD were more likely to be evening types. Looking at specific ADHD symptoms, individuals with more pronounced inattention were more likely to be evening types. The link of eveningness with inattention was stronger than with hyperactivity-impulsive symptoms.
Individuals with more pronounced ADHD symptoms were also more likely to have symptoms of depression and anxiety. However, the link with depression was stronger in individuals who were also evening types.
“By using a large, multisite sample of college students, we confirmed that students with elevated ADHD symptoms clearly differ from their peers without ADHD in their chronotype, with ADHD being associated with an evening chronotype. We also found that this association is primarily attributable to inattentive, rather than hyperactive–impulsive, symptoms. This study also showed, for the first time, that the association between ADHD inattentive symptoms and depressive symptoms is stronger for individuals with greater preference for eveningness,” the study authors concluded.
The study makes an important contribution to the scientific understanding of the links between ADHD and circadian rhythms. However, it also has limitations that need to be taken into account. Notably, the study design does not allow any cause-and-effect inferences to be made. Additionally, the study relied solely on self-report assessments. Results might not be the same if diagnoses of ADHD were made by clinicians.
The study, “ADHD, chronotype, and circadian preference in a multi-site sample of college students”, was authored by Stephen P. Becker, Aaron M. Luebbe, Michael J. Kofler, G. Leonard Burns, and Matthew A. Jarrett.