A Blue-Enriched, Increased Intensity Light Intervention to Improve Alertness and Performance in Rotating Night Shift Workers in an Operational Setting.

PURPOSE: This study examined the efficacy of a lighting intervention that increased both light intensity and short-wavelength (blue) light content to improve alertness, performance and mood in night shift workers in a chemical plant. PATIENTS AND METHODS: During rostered night shifts, 28 workers (46.0±10.8 years; 27 male) were exposed to two light conditions each for two consecutive nights (~19:00-07:00 h) in a counterbalanced repeated measures design: traditional-spectrum lighting set at pre-study levels (43 lux, 4000 K) versus higher intensity, blue-enriched lighting (106 lux, 17,000 K), equating to a 4.5-fold increase in melanopic illuminance (24 to 108 melanopic illuminance). Participants completed the Karolinska Sleepiness Scale, subjective mood ratings, and the Psychomotor Vigilance Task (PVT) every 2-4 hours during the night shift. RESULTS: A significant main effect of time indicated KSS, PVT mean reaction time, number of PVT lapses (reaction times > 500 ms) and subjective tension, misery and depression worsened over the course of the night shift (p<0.05). Percentage changes in KSS (p<0.05, partial η2=0.14) and PVT mean reaction time (p<0.05, partial η2=0.19) and lapses (p<0.05, partial η2=0.17) in the middle and end of night shift, expressed relative to start of shift, were significantly improved during the lighting intervention compared to the traditional lighting condition. Self-reported mood did not significantly differ between conditions (p>0.05). CONCLUSION: Our findings, showing improvements in alertness and performance with exposure to blue-enriched, increased intensity light, provide support for light to be used as a countermeasure for impaired alertness in night shift work settings.

Psychometric assessment of the Cardiac Depression Scale Short Form in cardiac outpatients.

BACKGROUND: Depression is common in patients with cardiovascular disease and is a risk marker for increased mortality. The valid and reliable detection of depression is fundamental to the appropriate management of these patients. AIM: The aim of this study was to evaluate the psychometric characteristics of the Cardiac Depression Scale Short Form 1 (DS-SF1) and the Cardiac Depression Scale Short Form 2 (DS-SF2) for screening cardiac outpatients in clinical settings. METHODS: Adult cardiac outpatients attending a cardiovascular clinic completed the Cardiac Depression Scale (CDS), two versions of the DS-SF (DS-SF1 and DS-SF2) and the Physical Health Questionnaire 2 (PHQ2-Y/N) prior to their cardiac consultation. RESULTS: Data from 326 patients (224 men; mean±SD age 66.25±14.39 years) were analysed. The DS-SF1 (mean score 16.28±5.70) had good construct validity with the CDS ( r=0.77; p<0.0001), adequate convergence with the PHQ2-Y/N ( r=0.59; p<0.0001) and good internal consistency (α=0.73). The DS-SF2 (mean score 15.80±6.80) had a better construct validity with the CDS ( r=0.84; p<0.0001) and the PHQ2-Y/N ( r=0.69; p<0.0001) and better internal consistency (α=0.82). The DS-SF2 showed strong criterion validity with the CDS with a DS-SF2 ⩾15 cut-point yielding 90% sensitivity and 73% specificity (area under the curve 0.92) for detecting depression (CDS ⩾95). CONCLUSION: These findings confirm the excellent psychometric properties of the DS-SF2 as an ideal tool for screening depression in cardiac patients in clinical practice. The DS-SF2 should be regarded as the definitive version of the DS-SF.