Light therapy for seasonal affective disorder with blue narrow-band light-emitting diodes (LEDs).

BACKGROUND: While light has proven an effective treatment for Seasonal Affective Disorder (SAD), an optimal wavelength combination has not been determined. Short wavelength light (blue) has demonstrated potency as a stimulus for acute melatonin suppression and circadian phase shifting. METHODS: This study tested the efficacy of short wavelength light therapy for SAD. Blue light emitting diode (LED) units produced 468 nm light at 607 microW/cm2 (27 nm half-peak bandwidth); dim red LED units provided 654 nm at 34 microW/cm2 (21 nm half-peak bandwidth). Patients with major depression with a seasonal pattern, a score of > or =20 on the Structured Interview Guide for the Hamilton Depression Rating Scale-SAD version (SIGH-SAD) and normal sleeping patterns (routine bedtimes between 10:00 pm and midnight) received 45 minutes of morning light treatment daily for 3 weeks. Twenty-four patients completed treatment following random assignment of condition (blue vs. red light). The SIGH-SAD was administered weekly. RESULTS: Mixed-effects analyses of covariance determined that the short wavelength light treatment decreased SIGH-SAD scores significantly more than the dimmer red light condition (F = 6.45, p = .019 for average over the post-treatment times). CONCLUSIONS: Narrow bandwidth blue light at 607 microW/cm2 outperforms dimmer red light in reversing symptoms of major depression with a seasonal pattern.     

The prehospital 12-lead electrocardiogram's effect on time to initiation of reperfusion therapy: a systematic review and meta-analysis of existing literature

The prehospital electrocardiogram (ECG) is becoming the standard of care of suspected cardiac chest pain. We evaluated the evidence regarding the prehospital ECG and sought to quantify the reduction in time to reperfusion therapy attributable to the prehospital ECG. We conducted a systematic review and analyzed studies that were conducted in emergency medical systems relevant to providers in the United States. The papers were limited to studies that reported original data that compared prehospital ECG to no prehospital ECG groups. Four studies containing 99 patients met the inclusion criteria. A meta-analysis of these studies revealed a difference of 24.7 (95% confidence interval, 16.7-32.7) minutes. Providers now have a quantified value of the prehospital ECG based on the best published evidence. In addition, this search showed a relatively low quality and quantity of research on the prehospital ECG.     

Near-ultraviolet radiation suppresses pineal melatonin content

UV radiation (200-400 nm) is generally considered to be outside the range of visible illumination for mammals. The aim of this study was to determine if UV wavelengths can influence pineal physiology. Experiments on hamsters confirm that wavelengths as low as 305 nm are transmitted through the clear ocular media to the retina. Furthermore, low irradiances of broadband (340-405 nm) and monochromatic (360 nm) UV radiation are capable of suppressing high nocturnal levels of pineal melatonin in intact, but not blind, hamsters. These data indicate that the hamster eye and neuroendocrine system are able to detect and respond to near-UV wavelengths.     

Light-induced plasma melatonin suppression in seasonal affective disorder

1. Subjects with seasonal affective disorder were exposed to 0, 500 and 1000 lux of white light for one hour beginning at 0300 hours. 2. Plasma samples were taken periodically and analysed for melatonin. 3. Plasma melatonin levels were suppressed by exposure to both 500 and 1000 lux light levels, suggesting that SAD patients show no neuroendocrine insensitivity to light but may show supersensitive responses to light.