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.
研究概览
研究类型
注册 (实际的)
联系人和位置
学习地点
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Eindhoven、荷兰、5626ND
- GGzE
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参与标准
资格标准
适合学习的年龄
- 成人
- 年长者
接受健康志愿者
取样方法
研究人群
描述
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
学习计划
研究是如何设计的？
设计细节
队列和干预
团体/队列 |
干预/治疗 |
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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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研究衡量的是什么？
主要结果指标
结果测量 |
措施说明 |
大体时间 |
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Change in depressive symptom severity (QIDS-SR)
大体时间：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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次要结果测量
结果测量 |
措施说明 |
大体时间 |
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Sustained change in depressive symptoms (QIDS-SR follow-up)
大体时间：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)
大体时间：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)
大体时间：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
大体时间：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
大体时间：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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合作者和调查者
研究记录日期
研究主要日期
学习开始 (实际的)
初级完成 (实际的)
研究完成 (实际的)
研究注册日期
首次提交
首先提交符合 QC 标准的
首次发布 (实际的)
研究记录更新
最后更新发布 (实际的)
上次提交的符合 QC 标准的更新
最后验证
更多信息
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