Table 1.
Overview of studies included in the narrative review.
| Circadian Rhythms Disruption | |||||||
|---|---|---|---|---|---|---|---|
| Reference | Country | Design | Sample | Mental Health Outcome | Assessment Measure | Light Exposure (Measure Unit) | Main Findings |
| Cho et al. [36] |
Korea | Cross-sectional study | 10 healthy young adults (21–34 years old) |
Sleep quality and brain activity during sleep | PSQI PSG |
Indoor LAN: fluorescent lamp (40 lux, 30 cm long), approximately 1 m away from participants’ eyes |
Increased stage 1 sleep, decreased slow-wave sleep, and increased arousal index during lights-on sleep. Theta power (4–8 Hz) during REM sleep, and slow oscillation (0.5–1 Hz), delta (1–4 Hz), and spindle (10–16 Hz) power during NREM sleep decreased in lights-on sleep. |
| Lahiri et al. [37] |
India | Comparative cross-sectional study | 263 participants from urban and 249 participants from rural areas (18–60 years old) |
Sleep quality | PSQI 10-item PSS |
Outdoor ALAN: nighttime radiance (1 radiance unit = 10−9 W/cm2/sr) |
Poorer sleep quality with higher nighttime radiance exposure. For urban participants, adjusted coefficient of 12.84 (95% CI: 12.31, 13.37) for exposure of >40.0 nW/cm2/sr. |
| Min & Min [35] |
South Korea | Population-based cohort study | 52,027 older adults from the NHIS-NSC cohort (≥60 years old) |
Insomnia | Hypnotic drugs prescription (zolpidem and triazolam) | Outdoor ALAN: satellite mapping of artificial light; light pollution levels (nanowatts/cm2/sr) | Regression coefficients for prescription days and daily defined doses of hypnotic drugs were significantly higher among people living in areas with higher outdoor artificial nighttime light. |
| Obayashi et al. [33] |
Japan | Cross-sectional study | 2947 adults (≥40 years old) |
Sleep quality (PSQI) Depressive symptoms |
PSQI GDS-15 |
Bedroom LAN (median intensity 1.0 lux) | Higher risk for sleep disturbances and depressive symptoms in groups with median LAN intensities ≥ 3 and ≥10 lux (sleep disturbances: OR 1.25, 95% CI 1.05–1.48, p = 0.011 for 3 lux; OR 1.29 95% CI 1.02–1.64; p = 0.034 for 10 lux; depressive symptoms: OR 1.30, 95% CI 1.05–1.61; p = 0.017 for 3 lux; OR 1.33, 95% CI 1.003–1.77; p = 0.047 for 10 lux). |
| Paksarian et al. [38] |
USA | Population-based, cross-sectional study | 10,123 adolescents; 6483 for behavior disorder outcomes (13–18 years old) |
Sleep patterns. Past-year mood, anxiety, behavior, and substance use disorders |
Modified version of the CIDI (v. 3.0 according to DSM-IV criteria). Self-reported habitual sleep patterns. Parent-reported information included in behavior disorder diagnoses |
Outdoor ALAN, transformed into units of radiance (nW/cm2/sr) |
Higher ALAN levels associated with later weeknight bedtime. Adolescents in the highest ALAN quartile went to bed 29 (95% CI, 15–43) minutes later and reported 11 (95% CI, 19–2) fewer minutes of sleep than those in the lowest quartile. Positive association between ALAN and prevalence of past-year mood and anxiety disorders: each median absolute deviation increase in ALAN associated with 1.07 (95% CI, 1.00–1.14) times the odds of mood disorders and 1.10 (95% CI, 1.05–1.16) times the odds of anxiety disorders. Association with BD (OR 1.19 [95% CI, 1.05–1.35]) at further analyses. |
| Patel [41] |
USA | Cross-sectional study | 282,403 MMSA inhabitants. County level: 2823 inhabitants (≥18 years old) |
Low/insufficient sleep | MMSA: self-reports of sleep hours and insufficient sleep. County level: prevalence of insufficient sleep |
Outdoor ALAN (nW/cm2/sr) | MMSA level: 10-unit increase in nighttime light associated with 5.59 min per day estimated decline in sleep and increase of 13.77% of the odds of reporting insufficient sleep (<7 h). County level: 10-unit increase in nighttime light associated with increase of 2.19% of the prevalence of insufficient sleep. |
| Randjelovic [39] |
Serbia | Interventional study | 30 young adults (university students) (20–22 years old) |
Sleep quality | PSQI | Blue light emission from LED blacklight screens | Reduction of total PSQI score from 6.83 ± 2.73 to 3.93 ± 1.68 after the intervention (p < 0.0001; d = 1.02). |
| Sun [40] |
China | Cross-sectional study | 7258 veterans (≥60 years old) |
Sleep quality | PSQI | 3-year outdoor ALAN exposure (nW/cm2/sr) |
ALAN exposure above the threshold associated with poorer sleep quality, with OR 1.15 (CI 95% 0.97–1.36) and 1.45 (CI 95% 1.17–1.78) at the 75th and 95th percentiles of ALAN against the threshold. Association of ALAN exposure with poor sleep quality more pronounced in veterans with depression. |
| Wang et al. [34] |
China | Population-based cross-sectional study | 20,994 children and adolescents (2–18 years old) |
Sleep disorders | SDSC (Chinese version) | Outdoor ALAN exposure from 0.02 to 113.48 nW/cm2/sr within 500 m of each participant’s residential address | Higher quintiles of outdoor ALAN exposure associated with an increase in sleep disturbances (total sleep scores) of 0.81 (95% CI 0.66–0.96) in Q2, 0.83 (95% CI 0.68–0.97) in Q3, 0.62 (95% CI 0.46–0.77) in Q4, and 0.53 (95% CI, 0.36–0.70) in Q5. Higher quintiles of exposure associated with OR for sleep disorder of 1.34 (95% CI 1.23–1.45) in Q2, 1.43 (95% CI 1.32–1.55) in Q3 1.31 (95% CI, 1.21–1.43) in Q4, and 1.25 (95% CI, 1.14–1.38) in Q5. |
| Mood symptoms | |||||||
| Esaki et al. [55] |
Japan | Cross-sectional study | 184 subjects with BD (18–75 years) |
Manic symptoms in BD patients | YMRS | Indoor ALAN bedroom light exposure (from bedtime to rising time assessed for 7 consecutive days using a portable photometer) | Prevalence of hypomanic states significantly higher in participants with an average light intensity at night exposure of ≥3 lux (36.7% versus 21.9%; p = 0.02), with significantly higher OR (2.15, 95% CI 1.09–4.22, p = 0.02) at the multivariable logistic regression analysis adjusted for BD type, depressive symptoms, sleep duration, and daytime physical activity. |
| Esaki et al. [54] |
Japan | Longitudinal study | 172 subjects with BD (18–75 years) |
Mood episode relapses in BD patients | Manic or hypomanic episodes (with or without mixed features) or depressive episodes according to the DSM-5 criteria |
Indoor ALAN bedroom light exposure (from bedtime to rising time assessed for 7 consecutive days using a portable photometer) |
Risk for manic/hypomanic relapses significantly higher with an average nighttime illuminance ≥ 3 lux (HR 2.54, 95% CI 1.33–4.84); significant relationship even at the multivariable model adjusted for a propensity score in relation to nighttime light (HR 2.17, 95% CI 1.04–4.52). No significant association between nighttime light and depressive relapses. |
| Helbich et al. [43] |
The Netherlands | Cross-sectional survey | 10,482 adults (18–65 years) |
Depressive symptoms | PHQ-9 | Outdoor ALAN satellite-based measures of radiances for exposure assessments (nW/cm2/s) |
Significantly higher PHQ-9 scores among people in the second to fifth ALAN quintile (βQ2 = 0.503, 95% CI 0.207–0.798, βQ3 = 0.587 95% CI 0.291–0.884, βQ4 = 0.921, 95% CI: 0.623–1.218, βQ5 = 1.322, 95% CI 1.023–1.620). ALAN risk estimates adjusted for individual and area-level confounders still significant for the 100 m buffer. |
| Liao [49] |
United Kingdom | Cohort study (secondary analysis of baseline data) | 200,393 adults | Depressive and anxiety symptoms; sleep patterns | Diagnostic category in the UKBB. Self-reports for sleep patterns |
Five-year mean NLE value | Higher NLE associated with higher depressed mood, higher tiredness/lethargy, and obesity. As for other determinants of mental health, association between higher NLE and higher air pollution, less green space, higher economic and neighborhood deprivation, and higher household poverty. Economic deprivation, household poverty, and waist circumference acting as bridge factors between key urban features and mental health symptoms. |
| Min & Min [46] |
Korea | Population-based, cross-sectional study | 113–119 participants for the assessment of depressive symptoms and 152–159 participants for the assessment of suicidal behavior; data from KCHS (≥20 years old) |
Depressive symptoms and suicidal behavior | CES-D (Korean version). Questions about attempted suicide or contemplated dying over the preceding 12 months |
Outdoor ALAN satellite data from the National Center for Environmental Information (from 0 to 63 nW/cm2/sr. Spatial resolution: 50–100 m and detection limit 10−9 W/cm2/sr) |
Higher likelihood of depressive symptoms and suicidal behaviors in participants living in areas with highest ALAN levels (OR 1.29, 95% CI: 1.15–1.46 and OR = 1.27, 95% CI: 1.16–1.39, respectively). |
| Ng [50] |
Malaysia | Prospective study | 169 pregnant women (20–48 years old) |
Depressive symptoms, anxiety, and stress. Sleep quality |
DASS-21 PSQI (second and third trimesters) |
Light exposure (H-LEA) | Higher lux level exposed from 10 pm to < 1 am associated with increased stress (β = 0.212, p = 0.037) and depression (β = 0.228, p = 0.024) in the third trimester. Poor sleep quality and higher light exposure at night attributed to greater stress and depression symptoms in the third trimester. Adverse effect of poor sleep quality on anxiety (β = 0.243, p = 0.002) and depression levels (β = 0.259, p = 0.001) in the second trimester. |
| Risk perception | |||||||
| Cleary-Gaffney et al. [23] |
Ireland | Cross-sectional study | 552 adults (≥18 years old) |
Citizens’ perceptions of ALAN exposure and its impact on psychological distress, cognitive failures, sleep quality, and chronotype | Light at night questionnaire. GHQ, CFQ, PSQI, MCTQ, MSI |
ALAN exposure in the sleeping environment | Perception of external ALAN in the sleeping environment associated with poorer sleep quality, cognitive impairment, and greater psychological distress. Internal lighting passing into the sleeping environment associated with poorer sleep quality but not with psychological wellbeing. Habitual use of light-emitting devices associated with poorer psychological wellbeing but not with sleep quality and timing. No associations between the perception of external ALAN and MSI scores. |
| Coogan et al. [56] |
Ireland | Cross-sectional survey | 462 adults (age ≥ 18 years old) |
Citizens’ perceptions of light pollution and its impact | 12-item questionnaire on light pollution | Outdoor ALAN perceptions of recent increase in light at night, the impact of light at night on sleep, changes in the timing of bird song, changes in the night time behavior of animals and changes in the number of bats seen | Perception of brighter night skies in urban settings, with public lighting reported as the main source of light at night. Neighbors’ domestic lighting reported as the most common source of ALAN for rural settings. Respondents from rural settings more likely to report sleep impairment due to ALAN. |
| Kim et al. [60] |
Korea | Cross-sectional survey | 1096 research subjects (20–50 years old) |
Citizens’ perceptions of light pollution and its impact and social amplification of risk | Survey on environmental and health risk factors, considering psychometric variables that influence risk perception | Outdoor ALAN (light trespass, over-illumination, glare, and light clutter) | Among the 11 environmental risk factors examined in the study, highest rank for light pollution variables reported for glare (5.78 points, fifth position), while over-illumination (5.17 points), light trespass (5.11 points), and light clutter (4.80 points) ranked ninth, tenth, and eleventh. Influence of all psychometric variables except for controllability on risk perception. |
Notes: ALAN = Artificial light at night: BD = Bipolar Disorder; CES-D = Center for Epidemiologic Studies Depression Scale; CFQ = Cognitive Failures Questionnaire; CI = Confidence interval; CIDI = Composite International Diagnostic Interview; DASS-21 = Depression, Anxiety, and Stress Scale; GDS-15 = short version of the Geriatric Depression Scale; GHQ = General Health Questionnaire; H-LEA = Harvard Light Exposure Assessment; HR = Hazard ratio; KCHS = Korean Community Health Survey; LAN = Light at night; MCTQ = Munich Chronotype Questionnaire; MMSA = metropolitan and micropolitan statistical area; MSI = Melatonin-suppression index; NHIS = The National Health Insurance Service; NHIS-NSC = NHIS-National Sample Cohort; NLE = Night-time light emission; OR = Odds ratio; PHQ-9 = Patient Health Questionnaire (9 items); PSG = polysomnography; PSQI = Pittsburgh Sleep Quality Index; PSS = Perceived Stress Scale; SDSC = Sleep Disturbance Scale for Children; UKBB = United Kingdom BioBank; YMRS = Young Mania Rating Scale.