Effectiveness of Light Therapy Across Seasons
Is the Antidepressant Effect of Light Therapy for People With a Depressive Disorder Comparable in the Spring/Summer vs Autumn/Winter?
This study investigates whether the antidepressant effects of bright light therapy (BLT) differ between the spring/summer season and the autumn/winter season in adults with depressive disorders. While BLT is an established treatment for seasonal affective disorder, increasing evidence suggests it may also be effective for non-seasonal depression. However, it remains unclear whether its effectiveness depends on seasonal variation in natural daylight exposure.
In this prospective study conducted in a routine clinical care setting, patients referred for depressive symptoms and a score of > 6 on the Quick Inventory of Depressive Symptomatology-Self-Report (QIDS-SR) receive BLT in a structured "Light Café" environment. Participants undergo daily morning light therapy sessions (30 minutes at 10,000 lux) for at least one week, with possible extension up to three weeks based on treatment response. A delayed-start design is used, where a subset of participants begins treatment two weeks later, allowing comparison with the natural course of depressive symptoms.
Depressive symptoms are assessed using the QIDS-SR at baseline, during treatment, and at follow-up (6 weeks and 3 months post-treatment). Sleep quality, chronotype, circadian timing, and side effects are also measured.
The primary objective is to compare the effectiveness of BLT across seasons. Secondary objectives include evaluating the persistence of treatment effects, assessing the change in sleep quality and day-to-day sleep-wake pattern, and exploring whether outcomes vary by chronotype, circadian phase, and patient characteristics.
This study aims to inform whether BLT should be considered a year-round treatment option for depressive disorders and to better understand factors influencing individual treatment response.
연구 개요
연구 유형
등록 (실제)
연락처 및 위치
연구 장소
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Eindhoven, 네덜란드, 5626ND
- GGzE
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참여기준
자격 기준
공부할 수 있는 나이
- 성인
- 고령자
건강한 자원 봉사자를 받아들입니다
샘플링 방법
연구 인구
설명
Inclusion Criteria:
- Adults aged 18 years or older
- Diagnosis of a depressive disorder (unipolar or bipolar), including both seasonal and non-seasonal depression
- Currently indicated for bright light therapy
- QIDS-SR score ≥ 6 at baseline
- Able to provide informed consent
- Sufficient proficiency in Dutch or English to complete questionnaires
Exclusion Criteria:
- Current (hypo)manic or mixed episode
- Current psychotic episode
- Severe suicidal ideation requiring immediate intervention
- Diagnosis of dementia
- QIDS-SR score ≤ 5 at baseline
- Age < 18 years
- Inability to provide informed consent
- Insufficient language proficiency to complete study questionnaires
- Initiation, dose change, or switch of antidepressant medication within 3 weeks before or during light therapy
- Long-term use of agomelatine
Relative Contraindications (require consultation with treating physician before participation):
- Pregnancy (first trimester)
- Diabetes or other systemic vascular diseases
- Eye conditions associated with increased light sensitivity
- Epilepsy
Medication-Related Considerations:
- Participants are advised not to start antibiotics during light therapy (existing courses should be completed prior to participation)
- Participants are advised to discontinue use of photosensitizing medications or topical agents during treatment
- Participants are asked to discontinue melatonin use during light therapy
- A wash-out period of 1 month is required after discontinuation of melatonin or short-term agomelatine use before starting light therapy
공부 계획
연구는 어떻게 설계됩니까?
디자인 세부사항
코호트 및 개입
그룹/코호트 |
개입 / 치료 |
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Spring/summer
Patients with a depression who received bright light therapy as part of routine clinical care.
For the purpose of the analyses, participants were categorized based on the season of treatment initiation, with this cohort including those who started treatment during the spring and summer seasons.
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Bright Light Therapy (BLT) will be administered according to Dutch depression guidelines, using Innolux LED light lamp (3800K, 10,000 lux).
BLT will be given for one work week (Mon-Fri), 7:30-10:30 AM, 30 mins/session.
Patients can have breakfast, read, or use devices.
Treatment effectiveness will be evaluated using Self-Rated Quick Inventory of Depressive Symptoms (QIDS-SR).
If remission is achieved (QIDS-SR < 6), no additional treatment is given.
If response is insufficient (QIDS-SR ≥ 6), 5 more sessions will be added in the following week, with maximum two extensions (1-3 weeks total).
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Autumn/winter
Patients with a depression who received bright light therapy as part of routine clinical care.
For the purpose of the analyses, participants were categorized based on the season of treatment initiation, with this cohort including those who started treatment during the autumn and winter seasons.
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Bright Light Therapy (BLT) will be administered according to Dutch depression guidelines, using Innolux LED light lamp (3800K, 10,000 lux).
BLT will be given for one work week (Mon-Fri), 7:30-10:30 AM, 30 mins/session.
Patients can have breakfast, read, or use devices.
Treatment effectiveness will be evaluated using Self-Rated Quick Inventory of Depressive Symptoms (QIDS-SR).
If remission is achieved (QIDS-SR < 6), no additional treatment is given.
If response is insufficient (QIDS-SR ≥ 6), 5 more sessions will be added in the following week, with maximum two extensions (1-3 weeks total).
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연구는 무엇을 측정합니까?
주요 결과 측정
결과 측정 |
측정값 설명 |
기간 |
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Change in depressive symptom severity (QIDS-SR)
기간: Baseline to end of treatment (approximately 1-3 weeks after initiation of light therapy)
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Depressive symptom severity is assessed using the Quick Inventory of Depressive Symptomatology - Self-Report (QIDS-SR), a validated 16-item questionnaire with total scores ranging from 0 to 27 (higher scores indicating greater symptom severity).
The primary outcome is the change in QIDS-SR score from baseline (pre-treatment) to end of light therapy.
The analysis compares changes between participants treated in the spring/summer season and those treated in the autumn/winter season, while accounting for the delayed-start control condition.
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Baseline to end of treatment (approximately 1-3 weeks after initiation of light therapy)
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2차 결과 측정
결과 측정 |
측정값 설명 |
기간 |
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Sustained change in depressive symptoms (QIDS-SR follow-up)
기간: End of treatment to 6 weeks and 3 months post-treatment
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Depressive symptom severity is assessed using the Quick Inventory of Depressive Symptomatology - Self-Report (QIDS-SR), a validated 16-item questionnaire with total scores ranging from 0 to 27 (higher scores indicating greater symptom severity).
This secondary outcome evaluates the persistence of treatment effects by comparing post-treatment scores to follow-up scores.
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End of treatment to 6 weeks and 3 months post-treatment
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Change in sleep quality (PSQI)
기간: Baseline to 6 weeks and 3 months post-treatment
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Sleep quality is measured using the Pittsburgh Sleep Quality Index (PSQI), a validated self-report questionnaire with total scores ranging from 0 to 21 (higher scores indicating poorer sleep quality).
The outcome reflects change in sleep quality following light therapy.
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Baseline to 6 weeks and 3 months post-treatment
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Chronotype (MEQ)
기간: Baseline (chronotype assessment), end of treatment (1-3 weeks after initiation of light therapy), 6 weeks post-treatment, and 3 months post-treatment
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Chronotype is assessed using the Morningness-Eveningness Questionnaire (MEQ).
This outcome examines whether baseline chronotype moderates changes in depressive symptom severity following light therapy.
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Baseline (chronotype assessment), end of treatment (1-3 weeks after initiation of light therapy), 6 weeks post-treatment, and 3 months post-treatment
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Adverse Events and Side Effects
기간: At the end of each treatment week, up to 3 weeks
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Side effects are assessed using a self-report questionnaire capturing the presence and severity of common light therapy-related symptoms (e.g., headache, eye irritation, sleep disturbances).
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At the end of each treatment week, up to 3 weeks
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Change in Sleep-Wake Pattern during treatment
기간: Twice weekly during treatment, up to 3 weeks
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Sleep timing, duration, quality and fragmentation, are assessed using a shortened sleep diary based on the Consensus Sleep Diary.
This outcome evaluates changes in sleep patterns during light therapy and their relation to treatment response.
Participants completed the diaries in the clinic on Mondays and Fridays, reporting retrospectively on their sleep during the preceding nights (i.e., Friday-Sunday nights for Monday entries and Monday-Thursday nights for Friday entries).
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Twice weekly during treatment, up to 3 weeks
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공동 작업자 및 조사자
연구 기록 날짜
연구 주요 날짜
연구 시작 (실제)
기본 완료 (실제)
연구 완료 (실제)
연구 등록 날짜
최초 제출
QC 기준을 충족하는 최초 제출
처음 게시됨 (실제)
연구 기록 업데이트
마지막 업데이트 게시됨 (실제)
QC 기준을 충족하는 마지막 업데이트 제출
마지막으로 확인됨
추가 정보
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