Light exposure via a head‐mounted device suppresses melatonin and improves vigilant attention without affecting cortisol and comfort

Abstract

We aimed at assessing whether a head-mounted light therapy device, enriched in blue wavelengths, suppresses melatonin secretion and improves vigilant attention in the late evening hours. We also assessed whether using such light device is associated with discomfort and physiological stress. Seventeen healthy young participants (eight females) participated in a counterbalanced within-subject design during which they were exposed for 2 hr before habitual sleep time to a blue-enriched light (1500 lx) or to a lower intensity red-light (150 lx) control condition, using a new-generation light emitting diode (LED) head-mounted device. Compared to the red light control condition, blue-enriched light significantly reduced melatonin secretion and reaction times during a psychomotor vigilance task while no significant differences were detected in discomfort and cortisol levels. These results suggest that, compared to a control condition, blue-enriched light, delivered by a new-generation head-mounted device, elicits typical non-visual responses to light without detectable discomfort and physiological stress. They suggest that such devices might constitute an effective alternative to standard light boxes.

Red visual stimulation in theGanzfeldleads to a relative overestimation of duration compared to green

“…It is possible that our choice of the color green over blue was a decisive factor for this result. Blue light is known to reduce nocturnal melatonin and thus leads to an increase in internal activation levels (Figueiro & Rea, 2010; Schmidt et al, 2018). It cannot be excluded that blue light might have some activating properties during the waking phase, especially in a situation of prolonged relaxation such as our MMGF session.…”

“…Moreover, only blue light, but not red and green light, has been shown to suppress melatonin release and to reduce its nocturnal level. Melatonin is a hormone that regulates circadian rhythms and thus influences internal activation levels (Cajochen et al, 2005; Figueiro & Rea, 2010; Schmidt et al, 2018). Therefore, when comparing different pairs of colors that appear to elicit activation and relaxation, respectively, the red–green pair emerges as a very good candidate.…”

Effects of light therapy on sleep and circadian rhythm in older type 2 diabetics living in long-term care facilities: a randomized controlled trial

“…During the intervention phase of four weeks, participants in the LT group wore Luminette light therapy glasses (Lucimed, Villers-Le-Bouillet, Belgium) with a corneal level of 1500 lux (blue-enriched white light at a wavelength of 468 nm), while the control group wore custom-made light therapy glasses identical in appearance to those of the LT group but emitting a corneal level of 0.3 lux (faint yellow light), which did not affect circadian rhythms ( 48 ). Luminette glasses can deliver the same light therapy as conventional light boxes operating at 10,000 lux ( 49 , 50 ). Both groups will wear their glasses every morning from 9:00 to 10:00 am.…”

The Influence of Light Wavelength on Human HPA Axis Rhythms: A Systematic Review

“…While the effects of light exposure parameters on melatonin levels and sleep behaviours have been systematically reviewed previously [28,39]), the impact on circulating cortisol (a key effector of circadian rhythms in peripheral tissues [3]) remains relatively less understood. Most notably, although it is accepted that bright light is more effective than dim light in altering cortisol secretions, it remains unclear whether light-induced changes in cortisol secretion are also dependent on the light spectrum, with some studies reporting a cortisol spectrum effect [10,[40][41][42] and others reporting spectrally dependent shifts in melatonin but not cortisol [43][44][45][46]. The light exposures tested in these studies included a range of combinations of circadian timing, duration, intensity and spectral distribution, presumably contributing to the different responses measured.…”