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The aim of this study is to determine the relative effectiveness of monocular and binocular light exposures, with and without selective blue-blocking filtering, on nocturnal melatonin suppression, subjective sleepiness, and visual performance of night shift workers.
Over the course of six, 5-hour study nights, 30 participants will be randomized to 6 study conditions, 1) binocular dim-light control unfiltered, (2) monocular dim-light control (one eye occluded), (3) unfiltered binocular, (4) unfiltered monocular (non-dominant eye occluded), (5) filtered binocular (both eyes filtered), (6) filtered monocular (non-dominant eye filtered, the other non-filtered). Saliva samples will be collected every 30 minutes for melatonin levels. Participants will also be asked to provide subjective sleepiness and visual performance will be assessed. Study nights will be separated by one week and each participant will be randomized to one of the six study conditions each night. All participants will see all conditions.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Unfiltered Monocular | Experimental | Unfiltered monocular with the non-dominant eye occluded. |
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| Filtered Binocular | Experimental | Filtered binocular with both eyes filtered. |
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| Filtered Monocular | Experimental | Filtered monocular with non-dominant eye filtered, the other non-filtered. |
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| Unfiltered Binocular | Experimental | Unfiltered binocular - neither eye will be filtered. |
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| Dim Light Control | Placebo Comparator | Dim light with no filters. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Filtered Eyewear | Device | Filtered binocular viewing condition will be produced by eyeglasses frames with orange-tinted blue-blocking filter, eliminating all optical radiation for wavelengths shorter than 540 nm. For the filtered monocular condition, only the lens on the eyeglasses frame on the non-dominant eye will be tinted with the blue-blocking filter. |
| Measure | Description | Time Frame |
|---|---|---|
| Melatonin Levels AUC | Melatonin levels to assess Melatonin Suppression. Saliva samples will be collected every 30 minutes for melatonin levels. | Each night for 6 study nights |
| Measure | Description | Time Frame |
|---|---|---|
| Karolinska Sleepiness scale to measure Subjective Sleepiness | Subjective sleepiness will be measured using the Karolinska Sleepiness scale. This 9-point scale scores range from 1-9, where 1 = "very alert," 3 = "alert," 5 = "neither alert nor sleepy," 7 = "sleepy, but no difficulty remaining awake," and 9 = "very sleepy, fighting sleep, an effort to remain awake." Full scale from 1-9. A higher number indicates greater sleepiness. |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Mariana Figueiro | Icahn School of Medicine at Mount Sinai | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Light and Health Research Center | Menands | New York | 12204 | United States |
overall results will be shared, not individual results
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| Release Date | Unrelease Date | Unrelease Date Unknown | Reset Date | MCP Release Number |
|---|---|---|---|---|
| Jun 25, 2026 |
| ID | Term |
|---|---|
| D007319 | Sleep Initiation and Maintenance Disorders |
| ID | Term |
|---|---|
| D020919 | Sleep Disorders, Intrinsic |
| D020920 | Dyssomnias |
| D012893 | Sleep Wake Disorders |
| D009422 | Nervous System Diseases |
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| Unfiltered Eyewear | Device | For the unfiltered binocular, the subjects will wear transparent eyeglasses frames with no optical power. Unfiltered monocular vision will be produced by an opaque eyepatch occluding the non-dominant eye. |
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| No Filters | Other | Dim lights with no filters. |
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| Each night for 6 study nights |
| Numerical Verification Task (NVT) | The NVT requires participants to compare 2 lists of 20 pairs of 5-digit numerals at 2 contrasts (0.2 and 0.8), and the response time required to complete the task is recorded as the performance measure. A faster response time indicates better visual performance. | Each night for 6 study nights |
| D001523 |
| Mental Disorders |