The study compared adults with and without ADHD. It included 391 Dutch adults: 202 patients aged 18 to 64 who had a clinical ADHD diagnosis, and 189 controls aged 17 to 65. People filled out questionnaires about their sleep, body clock, mood, and ADHD symptoms.
Signs of a delayed sleep pattern, where sleep is pushed much later than normal, were far more common in the ADHD group (25.8%) than in the control group (2.1%). In both groups, more hyperactivity went along with sleeping later and sleeping for less time. The same pattern showed up with being male, being younger, and having seasonal low mood.
Higher body weight was tied to shorter sleep on workdays in both patients and controls. The authors also looked for signs linked to metabolic syndrome, but that result did not reach the study's own cutoff for significance, and they said it needs more study.
Because this was a snapshot taken at one point in time, it cannot show what causes what. The control group was mostly young, higher-educated women, and some of the sleep and mood measures were not well tested, so the results should be read with care.
The numbers Stats and what the terms mean
The statistics behind the plain-language claims above.
- Bijlenga, 2011: signs linked to metabolic syndrome, p = .053.
What the terms mean:
- p is the chance of seeing a gap at least this big if there were no real difference. Below .05 is usually read as unlikely to be chance alone.
Source: Bijlenga D, van der Heijden K, Breuk M, et al.. Associations Between Sleep Characteristics, Seasonal Depressive Symptoms, Lifestyle, and ADHD Symptoms in Adults. Journal of Attention Disorders (2011). doi:10.1177/1087054711428965