Impact Of Everyday Light Exposure Patterns On Health

NCT ID: NCT06908395

Last Updated: 2025-07-10

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 62 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2024-11-18
• Study Completion Date: 2025-06-30

Brief Summary

The aim of the present study is to characterize everyday light conditions of younger and older adults and to consider them in relation to cardiovascular, metabolic and psychological health. An ambulatory assessment approach will be used over 12 days, measuring physiological parameters and daily thoughts, behaviors and experiences of different age groups using wearable technologies (e.g., light sensors, activity trackers, continuous glucose monitors) and smartphone-based self-reports (e.g., mood, vitality).

At the beginning of the study, the degeneration of the lens and retina of the participants is objectively quantified by ophthalmologists. On the last two days, participants will spend one working day in dim light and another in bright light in randomized order under the same measurement protocol as before in order to experimentally assess their sensitivity to light and its health effects.

Detailed Description

This study is designed as an observatory field study of characterizing younger and older adults' everyday life in terms of light exposure patterns as well as cardiovascular, metabolic and psychological health parameters over 10 days continuously through wearables and smartphone-based self-reports (ambulatory assessment period). On the first day of data collection, each participant will undergo an extensive eye examination at the Institute of Ophthalmology, particularly an Optical Coherence Tomography (OCT) scan will conducted and by means of a macular pigment reflectometer the difference between the light entering and leaving the eye across the visual spectrum will be determined as a marker of lense yellowing. Thereafter, participants start wearing the wearable sensors (continuous glucose monitors, light loggers worn as a necklace) and instructions on how to complete the smartphone-based self-report forms are provided. Participants are asked to take pictures of every food or drink (except of water) and upload these pictures through the m-Path app, these photos will be later linked to the continuous glucose monitor data. Data will be collected from the first evening onwards (ca. 18:00 h). After the ambulatory assessment period under free-living conditions, participants will spend the 11th and 12th day in a controlled office room environment from 08:30 to 17:00 h. In a randomized cross-over design, the 11th and 12th day will be spent in either bright (1250 lux) or dim office lighting (10 lux). On these days, participants will continue to wear the wearables and complete the expanded smartphone-based self-reports mostly similar to the 10-day ambulatory assessment period. Between day 11 and 12, participants will leave controlled conditions from 17:00 h on day 11 to 08:30 h on day 12. On day 11 and 12, participants will receive a standardized fluid meals for breakfast and lunch, and are otherwise instructed to avoid any food, caloric or caffeinated beverages between 08:30 and 17:00 h. On these two days, skin temperature sensors will be placed on four different skin regions, and blood pressure will be manually measured at regular intervals between 08:30 h and 17:00 h. After removing all wearables on day 12, the study ends at 17:30 h. Over these 12 days of data collection, participants will be asked to keep their bedtimes at home as consistent as possible between days, and on day 11 and 12 they will be instructed to come to the office facilities fasted without any caloric intake after 22:00 h on the previous evening of day 10 and 11, respectively.

The two comparative groups formed in this study consist of 30 younger adults (18-35 years) and 30 older adults (60-80 years), both females and males will be included, and the aim is to match both groups with respect to sex (i.e. ideally 15 women and 15 men per group). The age contrast in the two groups is chosen, as substantial differences in degeneration of the lenses and retina within the eye can be expected.

For the sample size calculation of n = 30 per group, we refer to Zauner et al. (Zauner et al., 2023), who created a procedure to calculate statistical power and required sample size for wearable light-logging data. For most light-logging metrics, their approach shows that for strong differences in light exposure patterns (i.e., winter vs. summer) even smaller samples are sufficient (n = 3-24). We do not expect that differences between age groups are that strong as seasonal differences. However, we are confident that effects of about d = 0.7 could be detected with our design (n = 30 per group). Considering some drop-out, we anticipate that we will have to enroll 70 participants in total.

With the primary hypothesis of this study being that younger and older individuals differ in their light exposure patterns in everyday life, the two main explorative goals of the AgeLight study are to:

• characterize light exposure patterns in younger and older adults and their link to cardiovascular, metabolic, and psychological health
• identify determining factors of an individual's sensitivity to light and its health effects (such as degeneration of the lens and retina)

Conditions

Healthy Male and Female Subjects; Healthy Elderly

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: OTHER
• Blinding Strategy: NONE

Study Groups

10 days ambulatory assessment + 1 office day in bright light + 1 office day in dim light

Day 11 is spent under laboratory conditions in bright (1250 lux) office lighting from 08:30 to 17:00 h. Day 12 is spent under laboratory conditions in dim (10 lux) office lighting from 08:30 to 17:00 h.

Group Type: EXPERIMENTAL

10-day ambulatory assessment in everyday life combined with two laboratory office days

Intervention Type: OTHER

Participants undergo a 10-day ambulatory assessment period wearing a continuous glucose monitor and a light logger as a necklace as well as completing short questionnaires through a smartphone app at regular intervals every day. On the first day, participants also undergo an extensive eye examination. Day 11 and 12 are spent in either dim or bright office lighting in randomized order.

10 days ambulatory assessment + 1 office day in dim light + 1 office day in bright light

Day 11 is spent under laboratory conditions in dim (10 lux) office lighting from 08:30 to 17:00 h. Day 12 is spent under laboratory conditions in bright (1250 lux) office lighting from 08:30 to 17:00 h.

Group Type: EXPERIMENTAL

10-day ambulatory assessment in everyday life combined with two laboratory office days

Intervention Type: OTHER

Participants undergo a 10-day ambulatory assessment period wearing a continuous glucose monitor and a light logger as a necklace as well as completing short questionnaires through a smartphone app at regular intervals every day. On the first day, participants also undergo an extensive eye examination. Day 11 and 12 are spent in either dim or bright office lighting in randomized order.

Interventions

10-day ambulatory assessment in everyday life combined with two laboratory office days

Participants undergo a 10-day ambulatory assessment period wearing a continuous glucose monitor and a light logger as a necklace as well as completing short questionnaires through a smartphone app at regular intervals every day. On the first day, participants also undergo an extensive eye examination. Day 11 and 12 are spent in either dim or bright office lighting in randomized order.

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• Age: 18-35 or 60-80 years old
• Voluntary participation, signed consent form
• Owns an Android or iOS Smartphone compatible with the m-Path App
• Generally healthy (self-reported)
• Non-smoker for at least 12 months (self-reported)

Exclusion Criteria

• Pregnancy (for female participants) (self-reported)
• Night-shift worker
• Eye diseases (e.g. glaucoma, age-related macular degeneration, diabetic retinopathy conditions after retinal detachment / retinal blood vessel occlusions)
• Pseudophakic eyes
• Psychological disorders: insomnia, depression, bipolar disorder and generalized anxiety disorder
• Wearing specially-filtered glasses

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 80 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

RWTH Aachen University

OTHER

Sponsor Role: lead

Responsible Party

Jan-Frieder Harmsen

Principal Investigator

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Jan-Frieder Harmsen, PhD

Role: PRINCIPAL_INVESTIGATOR

RWTH Aachen University

Locations

University hospital at RWTH Aachen

Aachen, , Germany

Countries

Germany

Provided Documents

Document Type: Study Protocol

View Document

Other Identifiers

EK 24-324

Identifier Type: -

Identifier Source: org_study_id