Summary of findings for the main comparison. High correlated colour temperature light versus standard illumination for improving mood and alertness in daytime workers.

High correlated colour temperature light versus standard illumination for improving mood and alertness in daytime workers
Patient or population: daytime workers Setting: offices Intervention: high correlated colour temperature light Comparison: standard illumination
Outcomes	Anticipated absolute effects (95% CI)		№ of participants Effective sample size* (studies)	Quality of the evidence (GRADE)
	Risk with standard illumination	Risk with CCT light
Alertness assessed with: CJL and KS Scale CLJ range 1 to 5 KS range 1 to 9 (worst) follow‐up: range 1‐3 months	‐‐	SMD** 0.69 lower (1.28 lower to 0.1 lower)	163 Effective sample size = 50 (2 CBA studies)	⊕⊝⊝⊝ Very low1
Mood (positive) assessed with: PANAS Scale from: 10 (worst) to 50 (best) follow‐up: 1 month	Mean standard positive mood 25.9	MD 2.08 higher (0.1 lower to 4.26 higher)	94 Effective sample size = 34 (1 CBA study)	⊕⊝⊝⊝ Very low1,2
Mood (negative) assessed with: PANAS Scale from: 10 (best) to 50 (worst) follow‐up: 1 month	Mean standard negative mood 13.7	MD 0.45 lower (1.84 lower to 0.94 higher)	94 Effective sample size = 34 (1 CBA study)	⊕⊝⊝⊝ Very low1,2
Adverse events ‐ eye discomfort follow‐up: 1 month	Mean standard adverse events 1.7	MD 0.23 lower (0.37 lower to 0.09 lower)	94 Effective sample size = 34 (1 CBA study)	⊕⊝⊝⊝ Very low1
* Effective sample sizes applied to correct for the unit‐of‐analysis error. ** As a rule of thumb, 0.2 Standard Deviations represents a small difference, 0.5 a moderate difference, and 0.8 a large difference. CI: confidence interval; CCT: correlated colour temperature; MD: mean difference; PANAS: Positive and Negative Affect Schedule; SMD: standardised mean difference.
GRADE Working Group grades of evidence High quality: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect. Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect.

¹ The assessment of risk of bias for non‐randomised studies starts at low‐quality evidence. We downgraded the level of evidence with one level, i.e. to very low quality, due to imprecision caused by a small sample size.

² We would have downgraded the level of evidence with one more level due to imprecision caused by wide confidence intervals that include a null effect but we had already reached a judgment of very low‐quality evidence.