LEDs for photons, physiology and food.

Lighting based on light-emitting diodes (LEDs) not only is more energy efficient than traditional lighting, but also enables improved performance and control. The colour, intensity and distribution of light can now be controlled with unprecedented precision, enabling light to be used both as a signal for specific physiological responses in humans and plants, and as an efficient fuel for fresh food production. Here we show how a broad and improved understanding of the physiological responses to light will facilitate greater energy savings and provide health and productivity benefits that have not previously been associated with lighting.

Mindfulness-based stress reduction and health-related quality of life in a heterogeneous patient population.

This study examined the effects of mindfulness-based stress reduction (MBSR) on health-related quality of life and physical and psychological symptomatology in a heterogeneous patient population. Patients (n=136) participated in an 8-week MBSR program and were required to practice 20 min of meditation daily. Pre- and post-intervention data were collected by using the Short-Form Health Survey (SF-36), Medical Symptom Checklist (MSCL) and Symptom Checklist-90 Revised (SCL-90-R). Health-related quality of life was enhanced as demonstrated by improvement on all indices of the SF-36, including vitality, bodily pain, role limitations caused by physical health, and social functioning (all P<.01). Alleviation of physical symptoms was revealed by a 28% reduction on the MSCL (P<.0001). Decreased psychological distress was indicated on the SCL-90-R by a 38% reduction on the Global Severity Index, a 44% reduction on the anxiety subscale, and a 34% reduction on the depression subscale (all P<.0001). One-year follow-up revealed maintenance of initial improvements on several outcome parameters. We conclude that a group mindfulness meditation training program can enhance functional status and well-being and reduce physical symptoms and psychological distress in a heterogeneous patient population and that the intervention may have long-term beneficial effects.

A multicenter study of the light visor for seasonal affective disorder: no difference in efficacy found between two different intensities.

Fifty-five patients with winter seasonal affective disorder (SAD) were treated with a light visor, a newly developed portable light-delivery system, in a controlled parallel design. A dim (400 lux) visor was compared with a bright (6000 lux) visor for either 30 or 60 minutes in the morning for 1 week. Response rates for these two treatments were 36% and 56%, respectively; the duration of treatment sessions did not affect outcome. There was no evidence that the brighter visor was superior in efficacy to the dimmer one. Significantly greater relapse occurred following withdrawal of the dimmer visor. Alternative explanations for these findings are that the light visor is acting as a placebo or that it is equally effective over a wide range of intensities.

Effects of green or white light for treatment of seasonal depression.

Twelve subjects with winter depression were treated with equal quanta of green or white light in a randomized crossover study. Each treatment condition consisted of 2 hours of exposure each morning for 1 week, with at least 1 interventing week without treatment. Ratings made without knowledge of treatment condition were done before and after each condition. Both treatments significantly reduced depression ratings. White light was significantly more effective than green light in reducing endogenous symptoms, but not the "atypical" symptoms that are common features of winter depression. Furthermore, sequence of treatment conditions influenced antidepressant responses. Broad-band white light may be optimal for maximizing therapeutic response.

Treatment of seasonal affective disorder with green light and red light.

OBJECTIVE: This study sought to determine whether an equal photon density of green light is superior to red light in treating seasonal affective disorder. METHOD: After recruitment through the media, 20 outpatients with seasonal affective disorder participated in a balanced-order crossover trial of 1 week of green light therapy compared with 1 week of red light therapy. Each treatment consisted of 2 hours of daily light treatment at home in the early morning. Ultraviolet light was excluded from both treatment conditions. The photon densities of the two treatments (2.3 x 10(15) photons/sec per cm2) were similar to those used in previous studies of therapy with 2500-lux white light. Fourteen patients completed the study. At least 1 week separated each treatment period to allow time for relapse. Effectiveness of treatment was assessed by analysis of variance of changes in ratings on the Hamilton Rating Scale for Depression. RESULTS: Although patients' expectations of the two treatments were similar, green light induced greater antidepressant effects than red light. A Sequence by Color interaction was also demonstrated. CONCLUSIONS: Green light provides a treatment effect superior to that of red light and similar to that seen in previous studies with white light. These results are consistent with the hypothesis that retinal photoreceptors mediate the antidepressant response in seasonal affective disorder. Identifying optimal wavelengths for light treatment is important in optimizing phototherapy efficacy.

Effects of different wavelengths in seasonal affective disorder.

The aim of this study was to compare the relative therapeutic efficacies of three different light sources for treating winter depression. A balanced incomplete block crossover design was employed, whereby all patients (n = 18) were randomly assigned to two out of the three treatment conditions: white, red and blue light. The degree of depression was assessed by the 21-item Hamilton Depression Rating Scale. The data suggest that at a photon density of 2.3 X 10(15) photons/s/cm2, white light has greater therapeutic benefit than red or blue light. It is clear that a larger sample population should be tested to confirm this result. This preliminary finding indicates that light sources currently in use for phototherapy could not be improved by narrowing the wavelengths provided and shifting them towards either end of the visible spectrum.

2- versus 4-hour evening phototherapy of seasonal affective disorder.

Seasonal affective disorder (SAD) has been successfully treated with bright light, and morning exposure has been deemed more effective than exposure at other times. Evening treatment may offer a practical advantage, but the optimal duration of exposure has not been established. Six SAD patients were treated at home for 1 week with 2500 lux of light given either from 6 p.m. to 8 p.m. or from 6 p.m. to 10 p.m. using a counterbalanced crossover design with a minimal withdrawal period of 1 week between conditions. Both treatments were effective in reversing SAD symptoms, but neither treatment was superior. These results suggest that evening phototherapy for as little as 2 hours may be a useful and reasonable alternative for the treatment of SAD.

Treatment of winter depression with a portable, head-mounted phototherapy device.

1. A portable, head-mounted device was developed for administration of light therapy. A randomized crossover protocol was used to test the therapeutic efficacy of this device, compared to a standard light box, for treatment of winter depression. 2. Depressive symptoms were significantly reduced by both the head-mounted device and the light box. 3. Therapeutic efficacy of the two devices was not significantly different. 4. The head-mounted device was rated by patients as significantly more convenient than the conventional light box; this may be important in improving patient compliance.