Estimation of illuminance on the south facing surfaces for clear skies in Iran

Background: Daylight availability data are essential for designing effectively day lighted buildings. In respect to no available daylight availability data in Iran, illuminance data on the south facing vertical surfaces were estimated using a proper method. Methods: An illuminance measuring set was designed for measuring vertical illuminances for standard times over 15 days at one hour intervals from 9 a.m. to 3 p.m. at three measuring stations (Hamadan, Eshtehard and Kerman). Measuring data were used to confirm predicted by the IESNA method. Results: Measurement of respective illuminances on the south vertical surfaces resulted in minimum values of 10.5 KLx, mean values of 33.59 KLx and maximum values of 79.6 KLx. Conclusion: In this study was developed a regression model between measured and calculated data of south facing vertical illuminance. This model, have a good linear correlation between measured and calculated values (r= 0.892)

Effects of light and caffeine on human sleepiness and alertness: A simulated driving experiment

This thesis examined the effects of a novel blue-green light intervention, together with caffeine, on sleepiness and driving performance in young adults, a population that is overrepresented in sleepiness-related road crashes. Light, caffeine, and the combination of light and caffeine each improved alertness after chronic-partial sleep deprivation to a greater extent than did a placebo. Each condition improved subjective sleepiness, objective psychomotor performance, and objective driving performance, with the greatest effect found for light and caffeine in combination. These findings have implications for interventions to reduce mortality and morbidity associated with road crashes

The effect of light on cognitive performance of partially sleep-deprived young drivers

Sleepiness remains a primary cause of road crashes, the major cause of death in young adults. Light is known to produce a direct alerting effect, but little is known about its effects on sleepy drivers. This study aimed to compare the effect of blue-green light and caffeine on young drivers’ cognitive performance after chronic-partial sleep loss

The effects of sleep loss on young drivers' performance: a systematic review.

Young drivers (18-24 years) are over-represented in sleep-related crashes (comprising one in five fatal crashes in developed countries) primarily due to decreased sleep opportunity, lower tolerance for sleep loss, and ongoing maturation of brain areas associated with driving-related decision making. Impaired driving performance is the proximal reason for most car crashes. There is still a limited body of evidence examining the effects of sleep loss on young drivers' performance, with discrepancies in the methodologies used, and in the definition of outcomes. This study aimed to identify the direction and magnitude of the effects of sleep loss on young drivers' performance, and to appraise the quality of current evidence via a systematic review. Based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach, 16 eligible studies were selected for review, and their findings summarised. Next, critical elements of these studies were identified, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) guidelines augmented to rate those elements. Using those criteria, the quality of individual papers was calculated and the overall body of evidence for each driving outcome were assigned a quality ranking (from 'very low' to 'high-quality'). Two metrics, the standard deviation of lateral position and number of line crossings, were commonly reported outcomes (although in an overall 'low-quality' body of evidence), with significant impairments after sleep loss identified in 50% of studies. While speed-related outcomes and crash events (also with very low-quality evidence) both increased under chronic sleep loss, discrepant findings were reported under conditions of acute total sleep deprivation. It is crucial to obtain more reliable data about the effects of sleep loss on young drivers' performance by using higher quality experimental designs, adopting common protocols, and the use of consistent metrics and reporting of findings based on GRADE criteria and the PRISMA statement

Narrative review: do spontaneous eye blink parameters provide a useful assessment of state drowsiness?

Most objective drowsiness measures have limited ability to provide continuous, accurate assessment of drowsiness state in operational settings. Spontaneous eye blink parameters are ideal for drowsiness assessment as they are objective, non-invasive, and can be recorded continuously during regular activities. Studies that have assessed the spontaneous eye blink as a drowsiness measure are diverse, varying greatly in respect to study design, eye blink acquisition technology and eye blink parameters assessed. The purpose of this narrative review is to collate these studies to determine 1) which eye blink parameters provide the best state drowsiness measures; 2) how well eye blink parameters relate to and predict conventional drowsiness measures and 3) whether eye blink parameters can identify drowsiness impairment in obstructive sleep apnoea (OSA) - a highly prevalent disorder associated with excessive sleepiness and increased accident risk. In summary, almost all eye blink parameters varied consistently with drowsiness state, with blink duration and percentage of eye closure the most robust. All eye blink parameters were associated with and predicted conventional drowsiness measures, with generally fair to good accuracy. Eye blink parameters also showed utility for identifying OSA patients and treatment response, suggesting these parameters may identify drowsiness impairment in this group

Bright light alone or combined with caffeine improves sleepiness in chronically sleep-restricted young drivers

Background: Young drivers are over-involved in sleepiness-related crashes. The alerting effects of bright light offer a potential countermeasure for driver sleepiness, either replacing or in conjunction with current countermeasures such as the use of caffeine. Methods: Thirty young (18–25) chronically sleep-restricted drivers drove in a simulator under randomized conditions of continuous bright light (‘Light,’ 500 nm, 230μw/cm2), caffeine (‘Caffeine,’ 100 mg caffeinated gum), or light and caffeine together (‘Light + Caffeine’), after driving under a placebo condition (‘Placebo,’ decaffeinated gum, 555 nm light, 0.3 μW/cm2) on three consecutive days. Using mixed-effects linear models, the associations between these conditions and physiological outcomes (EEG alpha and theta power, heart rate, and beat-to-beat intervals), driving performance (lateral lane and steering-related outcomes and lateral acceleration), and subjective sleepiness was assessed. Results: Relative to Placebo, all conditions improved driving performance outcomes (P < 0.0001), with effects of Light + Caffeine equal to Light but greater than Caffeine. Light + Caffeine reduced EEG alpha power more than Light or Caffeine (P < 0.0006), but ECG outcomes were generally worse under all conditions relative to Placebo. Subjective sleepiness improved under the Light + Caffeine condition only (P < 0.0001). Conclusions: Combining bright light and caffeine enhances their alerting effects on lateral lane variability and subjective sleepiness. A bright light could be a practical alternative to caffeine for sleepy drivers who avoid caffeine. The alerting effects of bright light could alleviate chronic community-level mild sleep restriction and provide on-road benefits to reduce severe injuries and fatal sleepiness-related crashes.</p