An environmental approach to mania makes it possible to “slow down the sun” and modulate the destabilizing effects of spring sunlight. More in this report.
As with sunshine, it appears that the regularity of circadian events is more salient to bipolar disorder than their specific duration. More in this report.
Rates of mania rise in the spring, and two new studies suggest that it’s the rapid increase in sunlight, rather than the amount of sunlight, that’s responsible for this trend. An analysis of hospital admissions found that the rate of change in sunlight was responsible for 20% of the seasonal variance in admissions for mania. Separately, a group of researchers from 32 countries linked the rate of increase in spring sunlight to an earlier onset of bipolar disorder. Those with early onsets of the illness also show greater vulnerability to spring mania throughout their lives.
These findings are consistent with past research and point to the role of circadian rhythms in bipolar disorder. Rapid changes in sleep, daily routines, or sunlight can stress the already fragile circadian systems of patients with bipolar disorder, triggering new episodes. A promising avenue for prevention is to decelerate those changes by gradually introducing new routines or-in the case of spring-slowing down the sun.
An environmental approach to mania called dark therapy may modulate the destabilizing effects of spring sunlight. Long used in European hospitals, traditional dark therapy involves keeping patients in a pitch-dark room overnight, from 6 PM to 8 AM. This protocol has recently been modified with glasses that block blue light, the wavelength responsible for the physiological effects of darkness. It turns out that melanopsin receptors in the eye, which regulate melatonin, respond only to this short wavelength.
Blue light blockers were recently tested in a randomized controlled trial of hospitalized mania. From 6 PM to 8 AM, patients either wore the glasses or-when sleeping-stayed in a pitch-dark room. After one week, the dark therapy group improved with an effect size (1.86) that compared favorably with medication studies.
Strong blue blockers and pitch darkness are critical to the success of dark therapy. The study used lenses from lowbluelights.com ($40 to $50), and less expensive options (Uvex S0360X glasses, $8 to $10) have been employed by other researchers. Blue blockers lack significant adverse effects, although they could cause depression if worn before 6 PM. Most patients find them calming. Interestingly, duration of sleep actually decreased slightly with these lenses, but regularity of sleep improved.[7,8] As with sunshine, it appears that the regularity of circadian events rather than their specific duration is most salient to bipolar disorder.
Dark therapy is a sensible intervention for spring mania, but could this approach also be used to prevent the problem? Possibly. For patients prone to spring mania, I recommend starting the glasses a few weeks before symptoms typically begin. To counter the rapid rise in sunlight, patients can start by wearing the glasses later in the evening (eg, 10 PM) and slowly move them up to the 6 PM to 7 PM range as the outside sun increases. The shifts should be gradual (eg by 30 to 60 minutes per week). If manic symptoms appear, move the glasses up to an earlier start time. If symptom free, the glasses could be slowly shifted to a later start time once the rapid flux in sunlight has passed (that timing depends on local conditions-see Appendix).
Spring flux is particularly harsh in the Sun Belt, where the angle of the sun takes a sharp turn, and in northern latitudes, where the length of day varies drastically. Although it is relatively mild where I practice (Winston-Salem, NC), my phones still ring off the hook when March rolls around. Mania is usually not pleasurable, and it often presents with mixed features in the spring. Depression is marked by delay; indecision, and avoidance and it can keep patients from seeking help when needed. In contrast, mixed states create a sense of desperation as the conflicting forces of anxiety and impulsivity overlap. These patients are quick to call for urgent help. It can be difficult to convince them of this new paradigm, but the physical and mental benefits of blocking nocturnal blue light make it a worthwhile venture. Keep a pair by your desk for patients to try on (and be sure to warn them that weight loss is a potential side effect).[9,10]
In most areas of the US, the steepest increase in sunlight occurs between March-April. In the following areas it occurs between April-May: Charleston, WV; Washington, DC; Pittsburgh and Philadelphia, PA; Annapolis, MD; Hartford, CT; Dover, DE; Trenton, NJ. In these areas it occurs between February-March: New York, NY; Providence, RI; Boston, MA; Manchester, NH; Montpelier, VT; Portland, MA; Portland, OR; Seattle, WA; Honolulu, HI. Some cities experience two peaks. For example, in San Antonio, TX and Houston, TX, the increase in light peaks in January-February and again in March-April. In several New England cities, it tends to peak in February-March, then slows from March to April, then peaks again in April-May (eg. New York, NY; Boston, MA; Hartford, CT).
1. Parker G, Hadzi-Pavlovic D, Bayes A, et al. Relationship between photoperiod and hospital admissions for mania in New South Wales, Australia.J Affect Disord. 2018;226:72-76.
2. Bauer M, Glenn T, Alda M, et al. Solar insolation in springtime influences age of onset of bipolar I disorder.Acta Psychiatr Scand. 2017;136:571-582.
3. Aguglia A, Borsotti A, Cuniberti F, et al. The influence of sunlight exposure on hospitalization in emergency psychiatry.Chronobiol Int. 2017;34:1413-1422.
4. Barbini B, Benedetti F, Colombo C. Dark therapy for mania: a pilot study.Bipolar Disord. 2005;7:98-101.
5. Tosini G, Ferguson I, Tsubota K. Effects of blue light on the circadian system and eye physiology.Mol Vis. 2016;22:61-72.
6. Henriksen TE, Skrede S, Fasmer OB, et al. Blue-blocking glasses as additive treatment for mania: a randomized placebo-controlled trial.Bipolar Disord. 2016;18:221-232.
7. Henriksen TE, Skrede S, Fasmer OB, et al. Blocking blue light during mania - markedly increased regularity of sleep and rapid improvement of symptoms: a case report. Bipolar Disord. 2014;16:894-898.
8. Henriksen TE. Darkness: the new mood stabilizer. Symposium presentation. International Society for Bipolar Disorders, Washington, D.C., 2017.
9. Cheung IN, Zee PC, Shalman D, et al. Morning and evening blue-enriched light exposure alters metabolic function in normal weight adults.PLoS One. 2016;11:e0155601.
10. Reid KJ, Santostasi G, Baron KG, et al. Timing and intensity of light correlate with body weight in adults. PLoS One. 2014;9:e92251.
11. Atmospheric Science Data Center. Data from NASA’s Surface meteorology and solar energy collection. Also see: http://solarinsolation.org.
Dr. Aiken is the Director of the Mood Treatment Center and an Instructor in Clinical Psychiatry at the Wake Forest University School of Medicine. He does not accept honoraria from pharmaceutical companies but receives honoraria from W.W. Norton & Co. for Bipolar, Not So Much, which he coauthored with James Phelps, MD.