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Seasonal Affective Disorder (Sad)

Essentials

  • Seasonal affective disorder (SAD) is a recurring disorder most commonly occurring in wintertime.
  • The primary mode of treatment is bright light therapy. The methods of treating ordinary depression can also be used Planning the Treatment of Patients with Depression.
  • Abnormal functioning of the internal clock has a central role in the pathogenesis of SAD.

Definition

  • In everyday language, seasonal affective disorder (SAD) is often called winter depression.
  • The syndrome is a seasonal form of depression typically with worse symptoms and recurrence in wintertime. In a small share of patients, SAD may appear in spring or summer.
  • The symptoms of subsyndromal seasonal affective disorder are similar to those of SAD but milder. People with subsyndromal seasonal affective disorder do not have an affective disorder but may later develop one.

Prevalence

  • The prevalence of full-blown SAD in the population is 1-2%.
  • Considerably more people, up to 25% of adults, have mild symptoms.

Symptoms and findings

  • The symptoms of SAD are similar to those of other types of depression but some symptoms that are atypical for other types of depression are pronounced in patients with SAD.
    • Hypersomnia (night-time sleep considerably longer in winter than in summer, yet not refreshing)
    • Increased appetite and craving for sweet foods (particularly foods containing carbohydrates or starch)
    • Weight gain (by a couple of kilograms, on average) during winter
    • More severe symptoms in the afternoon
  • Periods of affective syndrome recur at the same time each year but may be associated with any season.
    • Symptoms most commonly begin in October, increasing in severity over a few weeks, and start to fade in March.
  • Later in life, depressive episodes often become longer or the symptoms may become worse.

Diagnosis

  • According to the ICD-10 disease classification, SAD should be diagnosed either as recurrent depressive disorder (F33) or as bipolar affective disorder (F31). The diagnostic criteria are given in table T1.
    • In the ICD-11 disease classification that will come into force in the next few years, SAD (6A80.4 seasonal pattern of mood episode onset) is included in the diagnostic codes for recurrent depressive disorders (6A71 seasonal depressive disorder), and it can also be diagnosed in association with either type I (6A60) or type II (6A61) bipolar disorder.

Diagnosis of seasonal affective disorder (SAD) according to ICD-10

  1. Three or more episodes of affective disorder occurring with onset within the same 90-day period of the year for three or more consecutive years.
  2. Remissions occur within a particular 90-day period of the year.
  3. Seasonal episodes substantially outnumber non-seasonal episodes that may have occurred.

Treatment

  • In addition to bright light therapy, similar therapeutic principles are applied as for ordinary depression (see Planning the Treatment of Patients with Depression).
    • Treatment should be sufficiently long.
  • The more the clinical picture is predominated by atypical depressive symptoms, the better the expected response to bright light.

Treatment of seasonal affective disorder (SAD)

MethodImplementation
Bright light therapy http://pubmed.ncbi.nlm.nih.gov/15800134/ http://pubmed.ncbi.nlm.nih.gov/25942575/Visible white light directed on the face. Eyes should be kept open but not looking directly at the light. Light intensity 2 500-10 000 lux. Regularly in the morning for 30-60 min between 5 and 10 a.m., at least 5 mornings a week.
PsychotherapyCognitive behavioural therapy (CBT-SAD), including psychoeducation, study and reassessment of behavioural and thought patterns and development of alternative behavioural and thought patterns. Group sessions of 90 min. twice a week for 6 weeks.
Pharmacotherapy Bupropion for Preventing Seasonal Affective Disorder in Adults, Second-Generation Antidepressants for Seasonal Affective Disorder SadAntidepressant therapy, which can be interrupted in the summer
Self-treatmentAvoidance of sleep deprivation, fitness training 2-3 times/week (approx. 45-60 min at a time around 7-8 a.m. or 1-5 p.m.) and a healthy diet

Bright light therapy

  • Bright light therapy is the primary treatment for SAD.
    • It alleviates early-night insomnia, anxiety, hypersomnia and isolation more quickly than cognitive behavioural therapy.
    • As symptoms usually recur 1-3 weeks after the end of treatment, it should be continued for long enough. Bright light therapy can be performed either in courses of 1-2 weeks or uninterrupted on at least 5 days a week over the winter.
  • Visible white UV-filtered light is used for bright light therapy. During treatment, the eyes should be kept open and uncovered. This way, the light will fall on the face and go through the eyes all the way to the retina.
  • Bright light therapy should be interrupted in summertime and restarted in the autumn.
    • If SAD has been treated with an antidepressant, the medication should be tapered off in summertime, as far as possible.
    • Patients themselves can work out the individually most suitable light doses and treatment schedules.

Adverse effects and contraindications

  • The most common adverse effects (mild headache and eye irritation, and nausea) most commonly appear in the very beginning of therapy. They are usually mild and transient and can be eliminated by reducing the treatment dose.
    • No severe or permanent eye effects have been observed.
    • Light may provoke migraine attacks in predisposed individuals.
  • There are no absolute contraindications for bright light therapy.
    • In people with retinal or lens disease or a systemic disease damaging the retina, bright light therapy should only be started after an examination by an ophthalmologist.
    • SAD patients with mood swings should be treated with caution because, in individual cases, bright light therapy has led to mania.
    • As UV-light has been filtered out or is not produced by the light source, the treatment will not predispose the patient to skin cancer or to the aggravation of certain dermatological diseases, in the way that sunlight does.

Interactions and photosensitizing medication

  • As melatonin may have a photosensitizing effect, the size and timing of melatonin doses should be checked if the patient is taking melatonin as a medicine or as a food supplement. Melatonin should be taken as a single dose at night, no later than at 10 p.m.
  • No adverse interactions have been reported between antidepressants and bright light therapy.

Bright light therapy in practice

  • Correct positioning in relation to the bright light device is important for the success of treatment. For example, the person with SAD should sit close enough to the device to get the intended light dose.
    • The intensity of light on face level should exceed 2 500 lux.
  • Bright light therapy is usually given in the morning. To obtain the optimum response, bright light therapy should preferably be performed soon after waking.
  • Bright light is usually taken for 30-60 min. and no more than 2 h. At first, therapy should be performed on consecutive days. In most cases, the effect of bright light therapy can be seen within a week but for some people with SAD it will take at least 2-4 weeks for the effect to become apparent.

Criteria for referral

  • Patients with SAD can be treated in primary health care.
  • Consultation with specialized care is indicated
    • if treatment does not relieve symptoms
    • when the patient has other mental disorders in addition to SAD.

Follow-up

  • During treatment, the patient's health should be monitored according to a mutually agreed schedule.
    • Initially weekly, either at the surgery, remotely or by telephone
    • Later less frequently, but at least monthly
  • It should always be possible to make the follow-up more frequent and to intensify the treatment if necessary.

    References

    • Dollish HK, Tsyglakova M, McClung CA. Circadian rhythms and mood disorders: Time to see the light. Neuron 2024;112(1):25-40 [PubMed]
    • Chen ZW, Zhang XF, Tu ZM. Treatment measures for seasonal affective disorder: A network meta-analysis. J Affect Disord 2024;350:531-536 [PubMed]
    • Maruani J, Stern E, Boiret C, et al. Predictors of cognitive behavioral therapy for insomnia (CBT-I) effects in insomnia with major depressive episode. Psychiatry Res 2023;329:115527 [PubMed]
    • Rohan KJ, Burt KB, Norton RJ, et al. Change in Seasonal Beliefs Mediates the Durability Advantage of Cognitive-Behavioral Therapy Over Light Therapy for Winter Depression. Behav Ther 2023;54(4):682-695 [PubMed]
    • Wirz-Justice A, Terman AM. CME: Light Therapy: Why, What, for Whom, How, and When (And a Postscript about Darkness). Praxis (Bern 1994) 2022;110(2):56-62 [PubMed]
    • Pjrek E, Friedrich ME, Cambioli L, et al. The Efficacy of Light Therapy in the Treatment of Seasonal Affective Disorder: A Meta-Analysis of Randomized Controlled Trials. Psychother Psychosom 2020;89(1):17-24 [PubMed]
    • Geoffroy PA, Schroder CM, Reynaud E, et al. Efficacy of light therapy versus antidepressant drugs, and of the combination versus monotherapy, in major depressive episodes: A systematic review and meta-analysis. Sleep Med Rev 2019;48:101213 [PubMed]
    • Menculini G, Verdolini N, Murru A, et al. Depressive mood and circadian rhythms disturbances as outcomes of seasonal affective disorder treatment: A systematic review. J Affect Disord 2018;241:608-626 [PubMed]
    • Brouwer A, Nguyen HT, Snoek FJ, et al. Light therapy: is it safe for the eyes? Acta Psychiatr Scand 2017;136(6):534-548 [PubMed]
    • Partonen T, Lönnqvist J. Seasonal affective disorder. Lancet 1998;352(9137):1369-74 [PubMed]

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