Discover the most talked about and latest scientific content & concepts.

Concept: Light therapy


To develop a novel plasmonic nanosensing technique to monitor the exposure levels of UV light for sunlight disease prevention.

Concepts: Sunscreen, Sunburn, Nanoparticle, Light therapy, Ultraviolet, Gold, Sunlight, Sun


Although the light-induced melatonin suppression response is well characterized in adults, studies examining the dynamics of this effect in children are scarce. The purpose of this study was to quantify the magnitude of evening light-induced melatonin suppression in preschool-age children. Healthy children (n = 10; 7 females; 4.3 ± 1.1 years) participated in a 7-day protocol. On days 1-5, children followed a strict sleep schedule. On day 6, children entered a dim light environment (<15 lux) for 1-h before providing salivary samples every 20- to 30-min from the afternoon until 50-min after scheduled bedtime. On day 7, subjects remained in dim light conditions until 1-h before bedtime, at which time they were exposed to a bright light stimulus (~1000 lux) for 1-h and then re-entered dim light conditions. Saliva samples were obtained before, during, and after bright light exposure and were time anchored to samples taken the previous evening. We found robust melatonin suppression (87.6 ± 10.0%) in response to the bright light stimulus. Melatonin levels remained attenuated for 50-min after termination of the light stimulus (P < 0.008). Furthermore, melatonin levels did not return to 50% of those observed in the dim light condition 50-min after the light exposure for 7/10 children. Our findings demonstrate a robust light-induced melatonin suppression response in preschool-age children. These findings have implications for understanding the role of evening light exposure in the development of evening settling difficulties and may serve as experimental evidence to support recommendations regarding light exposure and sleep hygiene practices in early childhood.

Concepts: Hygiene, Phase response curve, Light therapy, Delayed sleep phase syndrome, Childhood, Sleep, Melatonin, Circadian rhythm



This study evaluates the influence of nightly pulsed-xenon ultraviolet light disinfection and dedicated housekeeping staff on surgical site infection (SSI) rates. SSIs in class I procedures were reduced by 46% (P = .0496), with a potential cost savings of $478,055. SSIs in class II procedures increased by 22.9%, but this was not significant (P = .6973). Based on these results, it appears that the intervention reduces SSI rates in clean (class I), but not clean-contaminated (class II) procedures.

Concepts: Light therapy, Hydrogen, Sun, Laser, Sunlight, Class II railroad, Ultraviolet, Antiseptic


Bat white-nose syndrome (WNS), caused by the fungal pathogen Pseudogymnoascus destructans, has decimated North American hibernating bats since its emergence in 2006. Here, we utilize comparative genomics to examine the evolutionary history of this pathogen in comparison to six closely related nonpathogenic species. P. destructans displays a large reduction in carbohydrate-utilizing enzymes (CAZymes) and in the predicted secretome (~50%), and an increase in lineage-specific genes. The pathogen has lost a key enzyme, UVE1, in the alternate excision repair (AER) pathway, which is known to contribute to repair of DNA lesions induced by ultraviolet (UV) light. Consistent with a nonfunctional AER pathway, P. destructans is extremely sensitive to UV light, as well as the DNA alkylating agent methyl methanesulfonate (MMS). The differential susceptibility of P. destructans to UV light in comparison to other hibernacula-inhabiting fungi represents a potential “Achilles' heel” of P. destructans that might be exploited for treatment of bats with WNS.

Concepts: Fluorescent lamp, Light therapy, Bacteria, Sun, Sunlight, Ultraviolet, Evolution, DNA


The factors that contribute to the development of psoriatic arthritis (PsA) among patients with psoriasis are not well known; however, systemic inflammation is believed to be important. On the basis of recent laboratory work demonstrating that major depressive disorder (MDD) is associated with increased systemic inflammation, we hypothesized that patients with psoriasis who develop MDD are at increased risk of subsequently developing PsA. We utilized The Health Improvement Network, a primary care medical records database, to identify 73,447 individuals with psoriasis. Patients were followed up to 25 years until the development of the primary outcome of PsA or the censor date. The exposure of interest was the development of MDD. Cox proportional-hazards models showed that patients with psoriasis who developed MDD were at significantly increased risk of subsequently developing PsA compared with patients who did not develop MDD, even after accounting for numerous covariates (hazard ratio 1.37, 95% confidence interval 1.05-1.80, P = 0.021). This result was maintained through numerous sensitivity analyses. These data support the hypothesis that MDD increases the risk of developing PsA among patients with psoriasis, suggesting a need for heightened prevention and management of MDD in patients with psoriasis.

Concepts: Cognitive behavioral therapy, Psoriasis, Primary care, Depression, Rheumatoid arthritis, Light therapy, Psoriatic arthritis, Major depressive disorder



The diurnal light cycle has a crucial influence on all life on earth. Unfortunately, modern society has modified this life-governing cycle by stressing maximum production and by giving insufficient attention to the ecological balance and homeostasis of the human metabolism. The aim of this study is to evaluate the effects of exposure or lack of exposure to natural light in a rest/activity rhythm on cortisol and melatonin levels, as well as on psychological variables in humans under natural conditions. This is a cross-sectional study. The subjects were allocated split into two groups according to their workspace (10 employees in the “with window” group and 10 in the “without window” group). All participants were women and wore anactigraph (Actiwatch 2, Philips Respironics), which measures activity and ambient light exposure, for seven days. Concentrations of melatonin and cortisol were measured from the saliva samples. Participants were instructed to collect saliva during the last day of use of the actigraph at 08:00 am, 4:00 pm and 10:00 pm. The subjects answered the Self-Reporting Questionnaire-20 (SRQ-20) to measure the presence of minor psychiatric disorders; the Montgomery-Asberg (MA) scale was used to measure depression symptoms, and the Pittsburgh Sleep Quality Index questionnaire (PSQI) was used to evaluate the quality of sleep. The Rayleigh analysis indicates that the two groups, “with window” an d “without window”, exhibited similar activities and light acrophases. In relation to light exposure, the mesor was significantly higher (t = -2.651, p = 0.023) in t he “with window” group (191.04 ± 133.36) than in the “without window” group (73.8 ± 42.05). Additionally, the “with window” group presented the highest amplitude of light exposure (298.07 ± 222.97). Cortisol levels were significantly different between the groups at 10:00 pm (t = 3.009, p = 0.008; “without window” (4.01 ± 0.91) “with window” (3.10 ± 0.30)). In terms of the melatonin levels, the groups differed at two different times of day: 08:00 am (t = 2.593, p = 0.018) and 10:00 pm (t = -2.939, p = 0.009). The “with window” group had a lower melatonin level at 08:00 am (3.54 ± 0.60) but a higher level at 10:00 pm (24.74 ± 4.22) than the “without window” group. Higher cortisol levels were positively correlated with minor psychiatric disorders and depressive symptoms (MA) at 10:00 pm. Lower melatonin levels at 10:00 pm were correlated with depressive symptoms and poor quality of sleep (PSQI). Our study demonstrated that not only may light pollution affect human physiology but also lack of exposure to natural light is related to high levels of cortisol and lower levels of melatonin at night, and these, in turn, are related to depressive symptoms and poor quality of sleep.

Concepts: Light therapy, Metabolism, Light, Ecology, Bipolar disorder, Over-illumination, Circadian rhythm, Melatonin


During the last half of the 20th century, the use of UVB therapy and photochemotherapy (PUVA), were one of the mainstays of treatment for psoriasis. However, accompanying to the advent of the most recent era of psoriasis, with targeted biologic therapy has been a decline in the frequency of phototherapy. This does not diminish its known clinical effects.

Concepts: Medicine, Sunlight, Light therapy, Therapy, Psoriasis, Ultraviolet, 20th century, 21st century


More than just a cosmetic concern, onychomycosis is a prevalent and extremely difficult condition to treat. In older and diabetic populations, severe onychomycosis may possibly serve as a nidus for infection, and other more serious complications may ensue. Many treatment modalities for the treatment of onychomycosis have been studied, including topical lacquers and ointments, oral antifungals, surgical and chemical nail avulsion, and lasers. Due to their minimally invasive nature and potential to restore clear nail growth with relatively few sessions, lasers have become a popular option in the treatment of onychomycosis for both physicians and patients. Laser or light systems that have been investigated for this indication include the carbon dioxide, neodymium-doped yttrium aluminum garnet, 870/930-nm combination, and femtosecond infrared 800-nm lasers, in addition to photodynamic and ultraviolet light therapy. This systematic review will discuss each of these modalities as well as their respective currently published, peer-reviewed literature.

Concepts: Oxygen, Fluorescent lamp, Light therapy, Sunlight, Light, Infrared, Laser, Ultraviolet