Circadian Factors in Mental Health

By Michael V. DeSanctis, Ph.D.
October 13, 2015

Sleeping InInherent to all living organisms is the principle of timing of biological functions. In humans, the interweaving of cognition, affect and physiology demands that we examine the role of clock or circadian factors in mental health.

A large data analytic literature on chronobiology exists. The intent of this article is to highlight how knowledge of circadian rhythms can be useful in everyday evaluation and treatment processes. The term circadian is derived from Latin, meaning “about a day” and is one of the most obvious cycles, involving night and day alternations. There are more frequent rhythms, known as ultradian rhythms, that cycle in about 90 minutes throughout the day. Alertness and performance are influenced by these rhythms.

The day length is fixed at 24 hours, but our internal clock runs slightly longer. Humans fall into two general chronotypes – the so-called owl and the lark on the ends of the continuum with intermediate manifestations of both chronotypes. There are also distinctive circadian high points and nadirs within the 24-hour day.

How often does a mental health clinician assess for chronotype before beginning a diagnostic interview or conducting psychotherapy? An owl seen at 6 p.m. can present in a very different manner than the owl seen for a 9 a.m. appointment. Are the appointment times dovetailing with the client and/or clinician’s needs? When is the clinician at peak mental performance? A clinician with an advanced circadian phase would probably do best seeing clients in the morning as opposed to later afternoon or evening. The converse would be true for therapists with delayed sleep phase patterns.

Neuropsychological test data could look quite different for the owl tested at 6 p.m. versus 8 a.m. Working memory, reaction time, information processing, level of alertness and motor coordination could all be impacted. Since many cognitive measurements utilize firm time limits for responding, this is potentially problematic and invites at the very least some additional interpretation of time or circadian factors in the results.

Due to circadian and ultradian influences, test sessions running three to four hours should be punctuated by rest breaks and take into consideration level of sleep deprivation and time of day. Daytime functional deficits in clients may be misconstrued as psychopathology, not circadian factors.

Circadian factors are amenable to adjustments. The power of light as a zeitgeber or entrainment mechanism, along with social stimuli, eating and physical activity has been documented. For seniors, exposure to light later in the day can mitigate sundowning and permit advanced circadian seniors to stay active later in the evening. When performing conjoint therapy, one needs to heed differences in chronotype among the partners, since these timing differences can exert a significant impact on the level of conflict and stress in the relationship and how people are getting their needs met.

If a client has just returned from an overseas or trans-continental trip spanning three or four time zones and is seen for a psychotherapy or diagnostic session, how will the clinician make adjustments in data gathering and interpreting the meaning of the results?

Individuals who work third shift and then seen for a session may derive less benefit than if they were seen prior to their overnight shift. Individuals with delayed sleep circadian patterns may function poorly in testing during early morning periods. Careless responses to test items, a tendency to hurry or impulsive reading of directions may occur. The neurocognitive impairments may be very subtle and involve possibly lapses in logic, inattentiveness, loss of focus or even micro-sleeping.

Resistance in clients may reflect a decrement in functioning associated with circadian and not necessarily personality or emotional variables. Individuals with delayed sleep phase syndrome often experience co-morbid mood disturbance.

Given the prevalence of sleep deprivation among contemporary adults and adolescents, the clinician needs to be aware of loss of focus, motivation and concentration and flashes of irritability that undermine the therapeutic intent either by late arrivals, missed appointments or failure to comply with inter-session assignments. Chronically tired individuals with depressed immune systems may complain of more pain or other somatic symptoms.

Fortunately, various forms of insomnia are quite amenable to CBT and other behavioral health strategies.

These illustrations reflect basic principles of timing. Seasonality is a broader corollary of these circadian ideas. As we know, winter SAD clients struggle with hypersomnolence and difficulty awakening in the morning. Light therapy in the morning may be quite helpful, both in terms of the antidepressant effect and the phase shifting that occurs such that the individual can more easily embrace the new day. Bright light in the morning can help delayed sleep sufferers re-regulate circadian rhythms.

Circadian factors may influence responses to psychotropic medications. Delayed circadian phase types may miss morning doses. How would a medicine with sedating effects impact an individual who is already tired from being misaligned with their natural circadian rhythm? Substance abuse by clients undermines natural circadian cycles. It is known for example that sleep architecture takes considerable time to normalize in recovery.

Awareness of circadian patterns can impact clinician wellness. Schedule breaks every two hours or so, if possible – many clinicians may see four, five or even six clients consecutively, a circumstance that can lead to reduced concentration, lapses in recall and perhaps digressive or tangential thinking or reduced empathic engagement.

Sleep deprivation and strenuous evening schedules delay the circadian pattern for many individuals, with predictable consequences the following day. Office lighting is important. Full spectrum fluorescent and large office windows admitting natural light are useful for keeping circadian rhythm entrained. Encouraging your clients to seek outdoor bright light experiences is not just a matter of improving mood or promoting exercise – the exposure to natural light helps entrain or re-synchronize one’s circadian pattern.

There are many good resources on circadian rhythms. The Society for Light Treatment and Biological Rhythms is one such resource. Another is the National Sleep Foundation. A peer reviewed scientific journal, Chronobiology International, is worth perusing. Circadian principles have been utilized for years in military, aerospace, aviation and industrial work performance applications, viz., the shift worker. The time seems opportune for mental health clinicians to embrace these concepts in their daily work so as to optimize client outcomes.

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Michael V. DeSanctis, Ph.D., ABPP, LP, CBSM, is a licensed psychologist, consultant on disability issues and is certified in behavior sleep medicine. Based in St. Paul, Minn., he now focuses on training and teaching after more than 30 years in private practice. His email address is:

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