Attention Deficit Hyperactivity Disorder and Delayed Sleep Phase Syndrome May Be Linked
The prevalence of certain sleep disorders such as obstructive sleep apnea, insomnia and restless legs syndrome is increased among children and adults with attention deficit hyperactivity disorder (ADHD).
Links between ADHD and a Circadian Disorder
In 1991, Dahl and colleagues reported a possible link between ADHD and a circadian disorder in their case report of a 10-year-old girl who had ADHD and delayed sleep phase insomnia. Chronotherapy with behavioral modification significantly improved her ADHD symptoms and increased her sleep time by approximately 29%. In 2000, Gruber and colleagues more objectively corroborated a possible link between ADHD and sleep-onset insomnia, based on actigraphy and sleep diary data.
In 2005, Van der Heijden and colleagues suggested that sleep-onset insomnia in children with ADHD was in actuality a symptom of delayed sleep phase syndrome (DSPS), based on the finding that the onset of dim light melatonin production was delayed.
Prevalence of ADHD
Some scientists now believe that ADHD and DSPS are linked and believe that an estimated 73-78% of children and adults with ADHD also have DSPS. In recent years, scientists have begun investigating whether treating DSPS in people with comorbid ADHD and DSPS improves ADHD symptoms.
People with ADHD have difficulty focusing on tasks (i.e., inattention) and may act impulsively. They may behaviorally be disorganized, restless and virtually always in motion (i.e., hyperactive). Symptoms of ADHD often begin in childhood and, in some people, continue into adulthood. Hyperactivity tends to improve by the teen years, whereas problems with inattention, disorganization and poor impulse control often continue into adulthood.
Pharmacological Treatment of ADHD
Stimulant medications are the first line of treatment for people with ADHD. Stimulant medications ironically reduce hyperactivity and impulsivity and improve a person’s ability to focus, work and learn. The reasons for this effect are unclear. A possible explanation may be that stimulants increase brain levels of the neurotransmitter dopamine, which is involved in thinking and attention.
Antidepressants such as tricyclic drugs (e.g., amitriptyline, desipramine) are sometimes used to treat adults with ADHD, although antidepressants are not approved for treating ADHD. Tricyclic drugs affect brain levels of norepinephrine and dopamine, which may enhance a person’s ability to focus and reduce hyperactivity.
Behavioral Therapy and ADHD
Behavioral therapy and psychological counseling can be helpful for people with ADHD. Behavioral therapy can involve maintaining a routine schedule; organizing everyday items; and, for children, using homework and notebook organizers, and giving praise or rewards when rules are followed. A therapist can help adults with ADHD with organizing their life with tools such as maintaining a routine and breaking large tasks into smaller tasks.
Delayed Sleep Phase Syndrome (DSPS)
In people with DSPS, the sleep/wake phases occur later than normal. Thus, they naturally want to go to sleep in the early morning hours (e.g., one to three hours after midnight) and awaken late in the morning (e.g., 10-11 am).
When trying to follow the societally “normal” schedule, people with DSPS have difficulty initiating sleep at night (i.e., insomnia) and difficulty awakening in the morning. When not following a “normal” schedule, the person’s sleep duration and quality is normal, but the sleep and wake phases are delayed. The disorder typically manifests during the teen years.
The goal of DSPS treatment is to shift the sleep/wake phases to a more socially “normal” time. This shift can be accomplished by bright light therapy, melatonin therapy and chronotherapy.
Bright Light Therapy
Bright light therapy is the strategic use of strong-intensity light to shift a person’s circadian phases earlier or later. The intensity of the light is stronger than that of natural light and can temporarily stop the production of melatonin.
Exposure to bright light soon after awakening advances the sleep/wake phases, whereas exposure to bright light soon before going to bed delays the sleep/wake phases.
People with DSPS typically undergo morning bright light therapy for several days to advance their sleep/wake phases. Once the phases are shifted to a desired time, the person then maintains bright light exposure at the same time daily to prevent the relapse of DSPS.
Melatonin and DSPS
The sleep-promoting hormone melatonin is produced in the pineal gland, which receives signals from the eyes about light intensity. During the night, melatonin normally rises to its highest level and, during the daytime, it falls to its lowest level. To prevent sleep-onset insomnia, a person with DSPS takes melatonin a few hours before bedtime to increase the melatonin level and aid the onset of sleep at a desired time.
Chronotherapy and DSPS
In chronotherapy, the bedtime and awakening time of a person with DSPS is set one to three hours later each day over several days until the person’s sleep/wake phases occur at a desired time. The schedule is then strictly maintained at the desired hours to prevent a relapse of DSPS. In people with DSPS, the sleep/wake phases are already naturally delayed. Therefore, further delaying the phases to a desired time may be more efficacious than attempting to advance them in some people.
Pathophysiology of ADHD and DSPS
How ADHD and DSPS are pathophysiologically linked is unclear. Alterations in brain regions involved in sleep, wakefulness, learning, cognition and motor activity could be a possible link, as indicated in some recent research.
Cerebral blood flow and the activity of certain neural networks are altered in adults with ADHD. Some of the same areas are also involved in wake and sleep.
For example, Tan and colleagues demonstrated that, compared to healthy controls, adults with ADHD have reduced blood flow in the limbic network (which is involved in emotions and in certain aspects of sleep) and in subcortical regions (e.g., the basal ganglia, a group of specialized neurons at the base of the brain that are involved a variety of functions such as sleep/wake cycles, the control of voluntary motor movements, procedural learning, habit learning, eye movements, cognition and emotion).
Imeraj and colleagues suggest that altered circadian rhythms in people with ADHD may result from dysfunction of the locus coeruleus. The locus coeruleus is a blue-tinged area on the back of the brainstem near the cerebellum that is involved in the onset and offset of rapid eye movement sleep and in other aspects of sleep and wake, and in circadian rhythmicity. It is also involved in movement. In people with ADHD, the arousal processes involving the locus coeruleus may be altered.
Alterations in the pineal gland may be involved in the coexistence of ADHD and DSPS. The pineal gland produces melatonin and is involved in circadian rhythms and in circadian preference (i.e., whether a person is a “morning” person or an “evening” person). This gland also has a role in movement. Recent research indicates that the pineal gland volume is smaller in people with ADHD than in people without ADHD, and that people with ADHD tend to have an “evening” circadian preference, which may be related to the reduced volume.
Such findings are interesting. However, more studies are needed to determine whether ADHD and DSPS have a shared pathophysiology.
Treating DSPS and ADHD Concurrently
It would seem that treating DSPS in people with ADHD would impact ADHD symptoms. To test this possibility, Fargason and colleagues used bright light therapy to advance the circadian rhythms in people with coexisting ADHD and DSPS.
The researchers also assessed whether bright light therapy could reduce ADHD symptoms. The study participants underwent two weeks of morning bright light therapy, after undergoing a one-week baseline assessment.
All participants wore an actigraphy watch to monitor changes in nocturnal and diurnal activity levels.
The baseline and post-treatment onset of dim light melatonin production times were compared.
A questionnaire was used to measure ADHD symptoms.
Fargason found that bright light therapy significantly advanced the onset of dim light melatonin production. This phase advance was significantly correlated with a decrease in ADHD symptoms and in hyperactivity-impulsivity.
Based on these findings, Fargason suggests that bright light therapy could be a complementary treatment for adults with DSPS and ADHD symptoms.
Scientists have yet to definitively confirm that DSPS and ADHD are linked, although the possibility that DSPS is an aspect of ADHD appears to be gaining acceptance, as expressed by researcher Sandra Kooij at the 30th European College of Neuropharmacology Conference (Paris, France) in 2017: “It looks more and more like ADHD and sleeplessness are two sides of the same physiological and mental coin … If the connection is confirmed, it raises the intriguing question: Does ADHD cause sleeplessness, or does sleeplessness cause ADHD? If the latter, then we may be able to treat some ADHD by non-pharmacological methods, such as changing light or sleep patterns, and prevent the negative impact of chronic sleep loss on health.” Kooij cautions that all ADHD symptoms cannot be attributed to an abnormal circadian rhythm but believes that an abnormal circadian rhythm is an important element of ADHD.
Standard pharmacological treatments for ADHD often do not fully control ADHD symptoms. Residual symptoms in some people may result from underlying untreated DSPS.
In addition, the long-term use of drugs to treat ADHD can have adverse effects such as addiction and cardiovascular problems (e.g., heart valve problems, hypertension, stroke, arrhythmias and cardiomyopathy).
The finding that DSPS often coexists with ADHD may provide another treatment approach for some people with ADHD.
Adding DSPS treatment (bright light therapy, etc.) with the standard treatment could potentially reduce a person’s need for stimulant medications and provide more effective relief from symptoms.
- Walters AS, Silvestri R, Zucconi M, et al. Review of the possible relationship and hypothetical links between attention deficit hyperactivity disorder (ADHD) and the simple sleep related movement disorders, parasomnias, hypersomnias, and circadian rhythm disorders. Journal of Clinical Sleep Medicine. 2008;4:591-600.
- Dahl RE, Pelham WE, Wierson M. The role of sleep disturbances in attention deficit disorder symptoms: A case study. Journal of Pediatric Psychology. 1991;16:229-239.
- Gruber R, Sadeh A, Raviv A. Instability of sleep patterns in children with attention-deficit/hyperactivity disorder. Journal of the American Acadamy of Child and Adolescent Psychiatry. 2000;39:495-501.
- Van der Heijden KB, Smits MG, Van Someren EJ, et al. Idiopathic chronic sleep onset insomnia in attention-deficit/hyperactivity disorder: A circadian rhythm sleep disorder. Chronobiology International. 2005;22:559-570.
- Kooij S. Circadian rhythm and sleep in ADHD—cause or life style factor? 30th Annual ECNP Congress; held on September 2–5, 2017, 2017. Available at https://www.ecnp.eu/~/media/Files/ecnp/About%20ECNP/Press/2017/Kooij%20pr%20FINAL_Sunday.pdf?la=en; Paris, France.
- Bijlenga D, Vollebregt MA, Kooij JJS, et al. The role of the circadian system in the etiology and pathophysiology of ADHD: Time to redefine ADHD? ADHD Attention Deficit and Hyperactivity Disorders. 2019;11:5-19.
- Gradisar M, Dohnt H, Gardner G, et al. A randomized controlled trial of cognitive-behavior therapy plus bright light therapy for adolescent delayed sleep phase disorder. Sleep. 2011;34(12):1671-1680.
- Fargason RE, Fobian AD, Hablitz LM, et al. Correcting delayed circadian phase with bright light therapy predicts improvement in ADHD symptoms: A pilot study. Journal of Psychiatry Research. 2017;91:105-110.
- US Department of Health and Human Services, National Institutes of Health. Attention-deficit/hyperactivity disorder (ADHD): The basics. In. Bethesda, MD: National Institute of Mental Health; 2019. Available at https://www.nimh.nih.gov/health/publications/attention-deficit-hyperactivity-disorder-adhd-the-basics/index.shtml.
- Tan YW, Liu L, Wang YF, et al. Alterations of cerebral perfusion and functional brain connectivity in medication-naive male adults with attention-deficit/hyperactivity disorder. CNS Neuroscience and Therapeutics. 2019. doi: 10.1111/cns.13185.
- Imeraj L, Sonuga-Barke E, Antrop, I, et al. Altered circadian profiles in attention-deficit/hyperactivity disorder: An integrative review and theoretical framework for future studies. Neuroscience and Biobehavioral Reviews. 2012;36:1897-1919.
- Bumb JM, Mier D, Noelte I, et al. Associations of pineal volume, chronotype and symptom severity in adults with attention deficit hyperactivity disorder and healthy controls. European Neuropsychopharmacology. 2016;26:1119-1126.