March 26, 2008 — A study suggests that the central nervous system stimulant methylphenidate improves sleep patterns in adults with attention-deficit/hyperactivity disorder (ADHD).

Researchers found that the stimulant had a positive effect not only on polysomnographic recordings of sleep, reducing parameters such as sleep latency (the period between going to bed and going to sleep) and the number of nocturnal awakenings, but also on subjective sleep quality, said the study's lead author, Esther Sobanski, MD, head of the scientific working group on adult ADHD, Central Institute of Mental Health in Mannheim, Germany.

"The increase in sleep efficiency and the marked effect on sleep latency was paralleled by the subjective estimate of a more restorative sleep; for example, the patients rated their sleep better," Dr. Sobanski told Medscape Psychiatry.

The study also confirms that sleep problems related to ADHD continue from childhood into adulthood, she said. "These findings are important because sleep is a major problem for adult patients with ADHD and nonrestorative sleep can intensify ADHD symptoms during the day," she added.

Their results are published in the March 1 issue of the journal Sleep.

Few Studies in Adult ADHD

Although there has been much research on sleep problems among children with ADHD, few such studies exist for adults, the study authors note, probably because until relatively recently, ADHD was considered to be a disorder prevalent only in children and adolescents. The current prevalence of adult ADHD is believed to be approximately 4.4%.

The use of stimulants to treat sleep issues has also been widely studied in children, but again, there is presently only 1 small actigraphic study investigating this effect in adults with ADHD, they write.

The current study included 34 adult nonmedicated patients with ADHD who were recruited from the outpatient clinic at the Central Institute (24 without current psychiatric disorders) and 34 age-matched and sex-matched medication-free control subjects without psychiatric or sleep disorders.

For the investigators to obtain polysomnographic recordings, patients in both groups spent 2 consecutive nights in the sleep laboratory. The sleep parameters measured included total time in bed, sleep onset latency, sleep efficiency, sleep time/time in bed, and various parameters of rapid eye movement (REM) sleep. Patients also filled out self-rated questionnaires that provided information about sleep quality, restorative value of sleep, mood, fatigue, etc.

Ten of the patients in the ADHD group were treated with methylphenidate, the same compound (generic) used in such brand names as Ritalin (Novartis) and Concerta (Alza). These patients received the stimulant for a minimum of 26 days starting with 5 to 10 mg twice daily, with doses being adjusted depending on efficacy and adverse effects. The patients were reassessed with polysomnographic recordings and sleep questionnaires.

At baseline, all 34 patients in the ADHD sample displayed reduced sleep efficiency with longer sleep onset latency and more nocturnal awakenings, and they also had altered sleep architecture vs the control group. Of the 34 patients in the ADHD group, the 24 without comorbid psychiatric disorders had similar differences with the control subjects.

Significant Change in Sleep Latency

The patients treated with methylphenidate showed a significant reduction in sleep onset latency and improved sleep efficiency, as shown in the accompanying table.

Table. Sleep Parameters at Baseline and After Treatment With Methylphenidate

The stimulant's positive effects on sleep were also captured in the patients' subjective sleep estimates. Patients reported significant improvement in restorative sleep as well as shortened sleep latency.

"The researchers observed a reduced percentage of REM sleep in the patients with ADHD compared to controls, but the significance of this isn't clear," said Dr. Sobanski in an email interview.

"REM sleep is thought to be involved in cognitive processes like consolidation of procedural memory and (the lack of it) may add to the ADHD symptoms, but this is hypothetical since a correlation between REM sleep percentage and ADHD symptom severity has not been studied systematically," she noted.

Drug Has Direct and Indirect Effects

It is not clear precisely how this stimulant may work to affect sleep quality, but Dr. Sobanski believes that there might be both direct and indirect effects. "An indirect effect is that the decrease of ADHD symptoms during the day has a positive effect on the general mood and stress level of the patients and, thus, increases sleep quality. A direct pharmacological effect might be the reduction of restlessness in the patients, and that would facilitate sleep. That would fit in with our finding that the largest effect was found for sleep latency."

The study suggests that sleep characteristics in adults with ADHD are similar to those in children. "It shows that sleep problems are a relevant clinical problem in adults with ADHD and should be addressed in the clinical set-up," said Dr. Sobanski. "Sleep problems should be monitored if patients are started with methylphenidate," she added. "If they do not improve, further sleep-specific diagnostic procedures should start."

This was not an industry-supported study. Dr. Sobanski has participated in studies for methylphenidate and in speaking engagements for Eli Lilly and Janssen-Cilag Ltd. Coauthor Dr. Barbara Alm has participated in studies for methylphenidate and in speaking engagements for Eli Lilly and Wyeth. The other study authors have disclosed no relevant financial relationships.

Sleep. 2008;31:375-381.

Clinical Context

Study Highlights

• The study enrolled 34 adults diagnosed with ADHD based on criteria from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, along with 34 age-matched and sex-matched control subjects.
• All participants with ADHD had symptoms from childhood to adulthood and were free from psychotropic medications for at least 4 weeks before study entry. Patients with a comorbid substance abuse disorder, sleep apnea, or night-shift work were excluded from study participation.
• Of the 34 adults with ADHD, 24 were without comorbid psychiatric conditions.
• Participants underwent 2 consecutive nights of polysomnographic recordings. Subjective sleep parameters were measured with 2 validated questionnaires. Finally, participants completed 2 measures of ADHD symptoms.
• 10 patients with ADHD were treated with methylphenidate for at least 26 days before reassessment of sleep quality. The mean dose of methylphenidate among these participants was 36.7 mg per day.
• Compared with control subjects, all participants with ADHD displayed reduced sleep efficiency, with longer sleep onset latency and an increased number of nocturnal awakenings. They also had a higher percentage of stage 1 sleep and a lower percentage of REM sleep.
• Periodic leg movements of sleep were more common among subjects with ADHD vs control subjects.
• Sleep questionnaires confirmed polysomnographic data that patients with ADHD experienced longer sleep latencies and more frequent nocturnal awakenings. However, overall sleep quality and the feeling of refreshment in the morning were similar between the patient and control groups.
• Methylphenidate reduced sleep onset latency and improved sleep efficiency, but the other polysomnographic variables remained unchanged. Methylphenidate was more effective on subjective measures of sleep, improving evening mood, sleep latency, nocturnal awakenings, and psychosomatic symptoms when falling asleep.
• Methylphenidate also improved subjective measures of the restorative value of sleep in patients with ADHD vs no medication.

Pearls for Practice

• ADHD can increase sleep latency and daytime somnolence, reduce REM sleep, and increase periodic limb movements in sleep among children.
• The current study demonstrates that methylphenidate reduces sleep latency and nocturnal awakenings and improves the subjective restorative value of sleep among adults with ADHD.

CME Test