This review pooled 13 case-control studies, drawn from 8,812 references, that compared adults diagnosed with ADHD to adults without it. Ages ran from about 19 to 40 years. Some comparison groups were healthy, while others had other psychiatric conditions. Medication use varied across studies, only one study was medication-free, and only one excluded other conditions.
On what people said about their own sleep, adults with ADHD differed on seven of nine measures. They took longer to fall asleep, reported more general sleep problems, and felt sleepier during the day. Two measures, how long they slept and how restful their sleep felt, did not differ between the groups.
When sleep was tracked by a wrist movement monitor, two of five measures differed. Adults with ADHD took longer to fall asleep and spent less of their time in bed actually asleep. When sleep was measured with overnight lab equipment, none of the measures that could be pooled differed.
The studies varied a lot from each other and were of modest quality (mean Newcastle-Ottawa score 5.5 of 9). The authors suggest that sleep complaints be screened during the clinical interview when adults are referred for an ADHD assessment, and that more research is needed to see whether these complaints match objective changes in sleep.
The numbers Stats and what the terms mean
The statistics behind the plain-language claims above.
- Díaz-Román, 2018, what people said about their sleep: time to fall asleep SMD 0.67; general sleep problems SMD 1.55; daytime sleepiness SMD 0.75.
- Díaz-Román, 2018, wrist movement monitor: time to fall asleep SMD 0.80; share of time in bed asleep SMD -0.68.
What the terms mean:
- SMD (standardized mean difference) is an effect size, read the same way as d: roughly, 0.2 is small, 0.5 is moderate and 0.8 is large. A minus sign shows the direction of the change, not its size.
Source: Díaz-Román A, Mitchell R, Cortese S. Sleep in adults with ADHD: Systematic review and meta-analysis of subjective and objective studies. Neuroscience & Biobehavioral Reviews (2018). doi:10.1016/j.neubiorev.2018.02.014