Occupational therapy in the management of seasonal affective disorder

Seasonal affective disorder (SAD) impacts a variety of occupational performance areas, and occupational therapists (OTs) help individuals cope with SAD by incorporating best practices and principles from various health care disciplines into their therapeutic practice with clients with SAD, including assessment, treatment, and evaluation. Care and treatment are holistic and tailored to the client’s goals, needs, and responsiveness to treatments.

In addition to educating clients on the etiology, prevalence, symptoms, and occupational performance issues associated with SAD, OTs treat patients or educate them on the different types of interventions available. In particular, OTs educate them on fatigue management and energy conservation, since low energy level is commonly reported in people with SAD.[1] The two main treatment approaches used by OTs are biomedical and psychosocial.

Biomedical approaches

The most commonly used biomedical treatment approaches are light therapy and pharmacotherapy.

Light therapy

Bright light therapy, or phototherapy, has been used to treat SAD,[2] with numerous studies citing its effectiveness.[3][4] Light therapy is recommended as a first-line treatment for SAD in Canadian, American, and international clinical guidelines.[4] The mood of individuals with SAD can improve with as little as 20 minutes of bright light exposure.[5] Bright light is more effective than dim light in protecting against “mood lowering” which commonly occurs in SAD.[5][6]p2

Light boxes are widely available devices which typically provide fluorescent light as a treatment for SAD.[2]

OTs should be familiar with typical usage guidelines provided to users of light boxes and emphasize to clients the need for clinical monitoring to ensure the appropriate doses of light.[2] Effective doses of light therapy vary depending on the individual. Studies have shown effective doses ranging between 3,000 lux 2 hours/day for 5 weeks[7] to 10,000 lux 30 minutes/day for 8 weeks.[4] Patients are typically advised to sit “within several yards” of the device and glance occasionally (rather than stare) at it.[8]p20 Commercial light boxes are not regulated by U.S. law and, as such, OTs should recommend medical consultation and advise caution when selecting and using them.[2][8] Only 41% of SAD patients comply with clinical practice guidelines and use light therapy regularly due to reasons of inconvenience and ineffectiveness.[9] As such, OTs can help clients develop methods for incorporating light therapy effectively into their daily routines and complying with clinical guidelines.[10]


Light therapy does not work for everyone – 20% to 50% of those diagnosed with SAD do not gain adequate relief from it.[11] In addition to the lack of efficacy, the required time commitment and the tendency for recurrence are additional reasons why individuals with SAD explore alternative treatments to light therapy.[12] In a study comparing the effectiveness of light therapy and an antidepressant medication, fluoxetine, evidence was found to support the effectiveness and tolerability of both treatments for SAD.[4]


Antidepressant medication (ADM) has been shown to be effective in treating various forms of depression.[13] Bupropion, a norepinephrine-dopamine reuptake inhibitor, was approved by the U.S. Food and Drug Administration (FDA)[14] for the prevention of seasonal affective disorder.[15] Other types of ADMs used to treat SAD include selective serotonin reuptake inhibitors (SSRIs) such as fluoxetine and sertraline, which appear to be effective.[16] OTs play a role in helping their clients understand how such medications, if prescribed, can decrease acute symptoms and lead to enhanced engagement in daily occupations.

ADMs are considered to be largely compensatory in nature.[13] In other words, ADMs may suppress depressive symptoms while they are being used, but lasting changes are not guaranteed once treatment is discontinued. A growing body of evidence is showing that psychosocial approaches to therapy, such as cognitive and behavioural interventions, may have more enduring effects than biomedical interventions.[13]

Psychosocial approaches

OTs also implement and recommend psychotherapeutic interventions, which follow psychosocial rehabilitation and recovery-based approaches.

The roles of OTs in psychosocial rehabilitation include the following:

  • Identifying the clients' psychosocial issues, strengths and limitations associated with the condition
  • Assessing clients’ readiness, motivation, and belief in their abilities to make changes in their lives
  • Identifying what is meaningful to the client
  • Identifying social support systems that are available to help the client achieve their goals.[17]

OTs use guiding frameworks such as the Canadian Model of Occupational Performance[18] and the Model of Human Occupation[19] to help clients set rehabilitation goals and identify areas of occupational performance that are affected by the symptoms associated with SAD.

Several types of interventions fall within the psychosocial scope of occupational therapy, and are used by an interdisciplinary team of health care providers who work with clients with SAD. In a health-care system that is driven largely by medical models, OTs promote psychosocial rehabilitation and recovery when addressing the underlying issues associated with SAD.[20] OTs use clinical reasoning to draw holistically upon principles of a variety of treatment approaches when implementing individual and group therapy among clients with SAD.

Group therapy

OTs in mental health settings often lead groups for inpatients and outpatients with mood disorders.[21] Some group therapy topics that target occupational performance issues related to SAD could include:

  • Stress management
  • Weight control and nutrition
  • Smoking cessation
  • Substance abuse
  • Time management
  • Social skills and networking
  • Wintertime activities
  • Sleep education
  • Self-esteem
  • Sexual health

These group therapy sessions are guided by a number of different theoretical and therapeutic frames of references, which use methods that are shown by research to be effective. Cognitive Behavioural Therapy, Mindfulness-Based Cognitive Therapy, Behavioural Activation, Problem-Solving Therapy, Positive Psychotherapy, Self-System Therapy and Outdoor Therapy are some of the more common approaches that OTs use when framing their interventions for client with SAD.

Cognitive behavioural therapy

Cognitive behavioural therapy (CBT) is used by OTs to treat SAD and other mood disorders. Originally developed by Beck and colleagues,[22] CBT aims to help clients identify the expectations and interpretations that can lead them towards depression and anxiety; adjust to reality; and break through their avoidances and inhibitions.[23] When implemented appropriately, it can help people change their cognitive processes, which may then correspond with changes in their feelings and behaviours.[24] CBT for SAD focuses on the early identification of negative anticipatory thoughts and behavior changes associated with the winter season, and helps clients develop coping skills to address these changes.[25]

By adopting a CBT approach, OTs can help clients with SAD engage in pleasurable activities in the winter months (i.e. behavioral activation) and help people think more positively (i.e. cognitive restructuring).[25] If qualified, OTs can deliver CBT skills training groups to SAD patients. The skills that OTs teach can have a direct impact on occupational performance issues and can include:[25]

  • developing a repertoire of wintertime leisure interests
  • using diaries to record automatic negative thoughts
  • creating a balanced activity level
  • improving time management skills
  • problem solving about situations that initiate negative thinking
  • setting goals and plans for maintaining gains and preventing relapse

CBT, or a combination of CBT and LT, can lead to a significant decrease in levels of depression amongst those with SAD.[10][12] With non-seasonal depression, CBT appears to be about as effective as ADM in terms of acute distress reduction; however, the effects of CBT are shown to be longer lasting than ADM.[13][26] There have been no direct comparisons made between CBT and ADM specifically for SAD.[25] CBT is effective in treating both mild and more severely depressed patients, and is shown to prevent or delay the relapse of depressive symptoms better than other treatments for depression.[25][27] There are no known adverse physical side effects of CBT.[25]

Mindfulness-based cognitive therapy (MBCT)

Mindfulness-based cognitive therapy (MBCT) is an intervention that aims to increase meta-cognitive awareness to the negative thoughts and feelings associated with relapses of major depression.[28] Unlike CBT, MBCT does not emphasize changing thought contents or core beliefs related to depression. It instead focuses on meta-cognitive awareness techniques, which are said to change the relationship between one’s thoughts and feelings.[29]

The act of passively and repetitively focusing one’s attention on the symptoms, meanings, causes, and consequences of the negative emotional state of depression is called rumination.[30] MBCT aims to reduce rumination by addressing the cognitive patterns associated with negative thinking and cultivating mindfulness through meditation and self-awareness exercises.[31] Once awareness of feelings and thoughts are cultivated, MBCT emphasizes accepting and letting them go.[31]

OTs can train clients with SAD in MBCT skills, which often takes place in a group setting over a number of weeks. Training focuses on the concept of “decentering,” which is the act of taking a present-focused and non-judgmental stance towards thoughts and feelings.[31] By learning how to decenter, a person can distance himself from the negative thoughts and feelings that may affect occupational performance in areas such as eating healthily, maintaining social relationships and being productive at work. By bringing attention back to the present (e.g. by focusing on their breath), clients gradually begin to observe their thought processes rather than reacting to them, thus, facilitating occupational engagement.

Behavioural activation

Behavioural activation (BA) is considered to be a traditional form of psychotherapy.[32] It is based on activity scheduling and aims to increase the number of positively reinforcing experiences in a person’s life. BA has shown comparable efficacy with other psychosocial therapies such as CBT, as well as with ADM treatment among mildly to moderately depressed patients.[33] BA has the potential to be very effective when used in occupational therapy, as it focuses on occupying one’s time with activities and experiences that are meaningful, positive, and engaging to the client. As such, clients who have occupational performance issues in productivity, leisure, and self-care may benefit from such therapy.

Problem-solving therapies

This intervention involves the patient creating a list of problems, identifying possible solutions, choosing the best solutions, creating a plan to implement them, and evaluating outcomes with respect to the problem. Further studies are needed to better understand the conditions under which problem-solving therapy is effective for depression;[34] however, this type of therapy is compatible with occupational therapy approaches to SAD. The Canadian Occupational Performance Measure (COPM)[35] is a widely used instrument that supports clients working with OTs in identifying their occupational needs, setting goals, and assessing change in occupational performance. Similar to the use of the COPM, OTs can use problem-solving therapy to focus on client choice and empowerment – principles that are fundamental to psychosocial rehabilitation and recovery.[36]

Positive psychotherapy

Positive psychotherapy (PPT) works to increase positive emotions in depressed clients and enhance engagement and meaning in activities that take place in a person’s life. Seligman and colleagues[37] found that group PPT was effective in treating mild to moderate depression for up to one year after the treatment was terminated. They also found that individual PPT led to greater remission rates than non-PPT treatments plus pharmacotherapy.

Self-system therapy

Self-system therapy (SST) is based on the notion that depression arises from chronic failure to attain personal goals due to one’s inability to self-motivate and pursue their goals.[38] SST is designed to improve one's ability to self-regulate and attain personal goals by helping define goals, identify the steps needed to attain them, identify the barriers that are preventing progress, and create a plan for how the goals may be achieved. This intervention draws upon techniques from cognitive therapy and BA, but has an overall emphasis on self-regulation.

Outdoor therapy

Outdoor work has been used effectively as a therapy to treat those with mood difficulties during the winter season in Denmark.[39] As an example, horticulture groups have shown positive impacts on depressive symptoms, which can be associated with psychosocial adaptation leading to healthy occupational performance.[40] Similarly, outdoor walking can provide a “therapeutic effect” to individuals with SAD that is on par with light therapy.[41]

Assessment of SAD

OTs also play a role in assessing and providing ongoing evaluation of clients who have SAD or who are suspected to have SAD. Assessments are most often used to determine if a particular treatment is working and what aspects of the disorder require the most attention.

Two commonly used assessments for SAD are the Structured Interview Guide for the Hamilton Rating Scale for Depression –Seasonal Affective Disorder version (SIGH-SAD)[42] and the Beck Depression Inventory, 2nd edition (BDI-II).[43]

The SIGH-SAD is a semi-structured interview that includes 21 non-seasonal depression items and an extra 8-item SAD-specific subscale. The BDI-II is quicker to administer and contains 21 measures of depressive symptom severity, which also captures atypical symptoms that are common in SAD.


  1. ^ Rosenthal NE (2006) Winter blues: everything you need to know to bead seasonal affective disorder. New York: Guilford Press, ISBN 1609181859.
  2. ^ a b c d "New treatment options for seasonal affective disorder. Possible alternatives to bright white light are under investigation". The Harvard mental health letter / from Harvard Medical School 25 (5): 6–7. 2008. PMID 19039841. 
  3. ^ Paino, M.; Fonseca-Pedrero, E.; Bousoño, M.; Lemos-Giráldez, S. N. (2009). "Light-therapy applications for DSM-IV-TR disease entities". The European Journal of Psychiatry 23 (3). doi:10.4321/S0213-61632009000300005. 
  4. ^ a b c d Lam, R. W.; Levitt, A. J.; Levitan, R. D.; Enns, M. W.; Morehouse, R.; Michalak, E. E.; Tam, E. M. (2006). "The Can-SAD Study: A Randomized Controlled Trial of the Effectiveness of Light Therapy and Fluoxetine in Patients with Winter Seasonal Affective Disorder". American Journal of Psychiatry 163 (5): 805–812. PMID 16648320. doi:10.1176/appi.ajp.163.5.805. 
  5. ^ a b Virk, G.; Reeves, G.; Rosenthal, N. E.; Sher, L.; Postolache, T. T. (2009). "Short exposure to light treatment improves depression scores in patients with seasonal affective disorder: A brief report". International journal on disability and human development : IJDHD 8 (3): 283–286. PMC 2913518. PMID 20686638. doi:10.1901/jaba.2009.8-283. 
  6. ^ Aan Het Rot, M.; Benkelfat, C.; Boivin, D. B.; Young, S. N. (2008). "Bright light exposure during acute tryptophan depletion prevents a lowering of mood in mildly seasonal women". European Neuropsychopharmacology 18 (1): 14–23. PMID 17582745. doi:10.1016/j.euroneuro.2007.05.003. 
  7. ^ Ruhrmann, S.; Kasper, S.; Hawellek, B.; Martinez, B.; Höflich, G.; Nickelsen, T.; Möller, H. J. (1998). "Effects of fluoxetine versus bright light in the treatment of seasonal affective disorder". Psychological medicine 28 (4): 923–933. PMID 9723147. doi:10.1017/S0033291798006813. 
  8. ^ a b Howland RH. Somatic therapies for seasonal affective disorder. J Psychosoc Nurs Ment Health Serv 2009;47(1):17–20.
  9. ^ Schwartz, P. J.; Brown, C.; Wehr, T. A.; Rosenthal, N. E. (1996). "Winter seasonal affective disorder: A follow-up study of the first 59 patients of the National Institute of Mental Health Seasonal Studies Program". The American journal of psychiatry 153 (8): 1028–1036. PMID 8678171. 
  10. ^ a b Rohan, K. J.; Roecklein, K. A.; Lacy, T. J.; Vacek, P. M. (2009). "Winter Depression Recurrence One Year After Cognitive-Behavioral Therapy, Light Therapy, or Combination Treatment". Behavior Therapy 40 (3): 225–238. PMID 19647524. doi:10.1016/j.beth.2008.06.004. 
  11. ^ Rohan, K. J.; Lindsey, K. T.; Roecklein, K. A.; Lacy, T. J. (2004). "Cognitive-behavioral therapy, light therapy, and their combination in treating seasonal affective disorder". Journal of Affective Disorders 80 (2–3): 273–283. PMID 15207942. doi:10.1016/S0165-0327(03)00098-3. 
  12. ^ a b Rohan, K. J.; Roecklein, K. A.; Tierney Lindsey, K.; Johnson, L. G.; Lippy, R. D.; Lacy, T. J.; Barton, F. B. (2007). "A randomized controlled trial of cognitive-behavioral therapy, light therapy, and their combination for seasonal affective disorder". Journal of Consulting and Clinical Psychology 75 (3): 489–500. PMID 17563165. doi:10.1037/0022-006X.75.3.489. 
  13. ^ a b c d Hollon, S. D.; Stewart, M. O.; Strunk, D. (2006). "Enduring Effects for Cognitive Behavior Therapy in the Treatment of Depression and Anxiety". Annual Review of Psychology 57: 285–315. PMID 16318597. doi:10.1146/annurev.psych.57.102904.190044. 
  14. ^ "First drug for seasonal depression". FDA Consumer (U.S. Food and Drug Administration (FDA)) 40 (5): 7. 2006. PMID 17328102. 
  15. ^ Modell, J. G.; Rosenthal, N. E.; Harriett, A. E.; Krishen, A.; Asgharian, A.; Foster, V. J.; Metz, A.; Rockett, C. B.; Wightman, D. S. (2005). "Seasonal Affective Disorder and Its Prevention by Anticipatory Treatment with Bupropion XL". Biological Psychiatry 58 (8): 658–667. PMID 16271314. doi:10.1016/j.biopsych.2005.07.021. 
  16. ^ Moscovitch, A.; Blashko, C. A.; Eagles, J. M.; Darcourt, G.; Thompson, C.; Kasper, S.; Lane, R. M.; International Collaborative Group on Sertraline in the Treatment of Outpatients with Seasonal Affective Disorders (2004). "A placebo-controlled study of sertraline in the treatment of outpatients with seasonal affective disorder". Psychopharmacology 171 (4): 390–397. PMID 14504682. doi:10.1007/s00213-003-1594-8. 
  17. ^ Ikiugu, M. N. (2010). "The New Occupational Therapy Paradigm: Implications for Integration of the Psychosocial Core of Occupational Therapy in All Clinical Specialties". Occupational Therapy in Mental Health 26 (4): 343–353. doi:10.1080/0164212X.2010.518284. 
  18. ^ Law M, Polatajko H, Baptiste S, Townsend E. (2002) "Core concepts of occupational therapy". In: Townsend E (ed.) Enabling occupation: an occupational therapy perspective. Ottawa. Canadian Association of Occupational Therapists, ISBN 189543758X.
  19. ^ Kielhofner G. (1995) A model of human occupation — theory and application. Baltimore: Williams & Wilkins, ISBN 0781769965.
  20. ^ Krupa, T.; Clark, C. (2004). "Occupational therapy in the field of mental health: Promoting occupational perspectives on health and well-being". Canadian journal of occupational therapy. Revue canadienne d'ergotherapie 71 (2): 69–74. PMID 15152722. 
  21. ^ Sundsteigen, B.; Eklund, K.; Dahlin-Ivanoff, S. (2009). "Patients' experience of groups in outpatient mental health services and its significance for daily occupations". Scandinavian Journal of Occupational Therapy 16 (3): 172–180. PMID 18982528. doi:10.1080/11038120802512433. 
  22. ^ Beck AT, Rush JA, Shaw BF, Emery G. Cognitive therapy of depression. New York: Guilford Press; 1979, ISBN 0898629195.
  23. ^ Weinrach, S. G. (1988). "Cognitive Therapist: A Dialogue with Aaron Beck". Journal of Counseling & Development 67 (3): 159–164. doi:10.1002/j.1556-6676.1988.tb02082.x. 
  24. ^ Ikiugu MN. Psychosocial conceptual practice models in occupational therapy: building adaptive capability. St. Louis: Mosby Elsevier; 2007, ISBN 0323041825.
  25. ^ a b c d e f Rohan KJ. Coping with the seasons: A cognitive-behavioral approach to season affective disorder therapist guide. New York: Oxford University Press; 2009, ISBN 0199712417.
  26. ^ Driessen, E.; Hollon, S. D. (2010). "Cognitive Behavioral Therapy for Mood Disorders: Efficacy, Moderators and Mediators". Psychiatric Clinics of North America 33 (3): 537–555. PMC 2933381. PMID 20599132. doi:10.1016/j.psc.2010.04.005. 
  27. ^ Derubeis, R. J.; Hollon, S. D.; Amsterdam, J. D.; Shelton, R. C.; Young, P. R.; Salomon, R. M.; O'Reardon, J. P.; Lovett, M. L.; Gladis, M. M.; Brown, L. L.; Gallop, R. (2005). "Cognitive Therapy vs Medications in the Treatment of Moderate to Severe Depression". Archives of General Psychiatry 62 (4): 409–416. PMID 15809408. doi:10.1001/archpsyc.62.4.409. 
  28. ^ Segal ZV, Williams JMG, Teasdale JD. Mindfulness-based cognitive therapy for depression: a new approach to preventing relapse. New York: The Guilford Press; 2002, ISBN 1572307064.
  29. ^ Scherer-Dickson, N. (2004). "Current developments of metacognitive concepts and their clinical implications: Mindfulness-based cognitive therapy for depression". Counselling Psychology Quarterly 17 (2): 223–234. doi:10.1080/09515070410001728253. 
  30. ^ Nolen-Hoeksema, S. (2000). "The role of rumination in depressive disorders and mixed anxiety/depressive symptoms". Journal of Abnormal Psychology 109 (3): 504–511. PMID 11016119. doi:10.1037/0021-843X.109.3.504. 
  31. ^ a b c Hick, S. F.; Chan, L. (2010). "Mindfulness-Based Cognitive Therapy for Depression: Effectiveness and Limitations". Social Work in Mental Health 8 (3): 225. doi:10.1080/15332980903405330. 
  32. ^ Lau, M. A. (2008). "New developments in psychosocial interventions for adults with unipolar depression". Current Opinion in Psychiatry 21 (1): 30–36. PMID 18281838. doi:10.1097/YCO.0b013e3282f1ae53. 
  33. ^ Cuijpers, P.; Van Straten, A.; Warmerdam, L. (2007). "Behavioral activation treatments of depression: A meta-analysis". Clinical Psychology Review 27 (3): 318–326. PMID 17184887. doi:10.1016/j.cpr.2006.11.001. 
  34. ^ Cuijpers, P.; Van Straten, A.; Warmerdam, L. (2007). "Problem solving therapies for depression: A meta-analysis". European Psychiatry 22 (1): 9–15. PMID 17194572. doi:10.1016/j.eurpsy.2006.11.001. 
  35. ^ Law, M.; Baptiste, S.; McColl, M.; Opzoomer, A.; Polatajko, H.; Pollock, N. (1990). "The Canadian occupational performance measure: An outcome measure for occupational therapy". Canadian journal of occupational therapy. Revue canadienne d'ergotherapie 57 (2): 82–87. PMID 10104738. 
  36. ^ Kirsh, B.; Cockburn, L. (2009). "The Canadian Occupational Performance Measure: A tool for recovery-based practice". Psychiatric Rehabilitation Journal 32 (3): 171–176. PMID 19136349. doi:10.2975/32.3.2009.171.176. 
  37. ^ Seligman, M. E. P.; Rashid, T.; Parks, A. C. (2006). "Positive psychotherapy". American Psychologist 61 (8): 774–788. PMID 17115810. doi:10.1037/0003-066X.61.8.774. 
  38. ^ Strauman, T. J.; Vieth, A. Z.; Merrill, K. A.; Kolden, G. G.; Woods, T. E.; Klein, M. H.; Papadakis, A. A.; Schneider, K. L.; Kwapil, L. (2006). "Self-system therapy as an intervention for self-regulatory dysfunction in depression: A randomized comparison with cognitive therapy". Journal of Consulting and Clinical Psychology 74 (2): 367–376. PMID 16649881. doi:10.1037/0022-006X.74.2.367. 
  39. ^ Hahn, I. H.; Grynderup, M. B.; Dalsgaard, S. B.; Thomsen, J. F.; Hansen, Å. M.; Kærgaard, A.; Kærlev, L.; Mors, O.; Rugulies, R.; Mikkelsen, S.; Bonde, J. P.; Kolstad, H. A. (2011). "Does outdoor work during the winter season protect against depression and mood difficulties?". Scandinavian Journal of Work, Environment & Health 37 (5): 446–449. PMID 21359494. doi:10.5271/sjweh.3155. 
  40. ^ Fieldhouse J. (2003). "The impact of an allotment group on mental health clients' health, wellbeing and social networking". Br J Occup Ther 66 (7): 286–296. 
  41. ^ Wirz-Justice, A.; Van Der Velde, P.; Bucher, A.; Nil, R. (1992). "Comparison of light treatment with citalopram in winter depression: A longitudinal single case study". International clinical psychopharmacology 7 (2): 109–116. PMID 1487622. doi:10.1097/00004850-199211000-00008. 
  42. ^ Williams JB, Link MJ, Rosenthal NE, Amira L, Terman M. Structured interview guide for the Hamilton depression rating scale – seasonal affective disorder version (SIGH-SAD). New York: New York State Psychiatric Institute; 1992.
  43. ^ Beck AT, Steer RA, Brown GK. Beck depression inventory – 2nd edition manual. New York: Guilford Press; 1996.
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.