Changing color and intensity of LED lighting across the day impacts on circadian melatonin rhythms and sleep in healthy men

Abstract

We examined whether dynamically changing light across a scheduled 16-h waking day influences sleepiness, cognitive performance, visual comfort, melatonin secretion, and sleep under controlled laboratory conditions in healthy men. Fourteen participants underwent a 49-h laboratory protocol in a repeated-measures study design. They spent the first 5 hours in the evening under standard lighting, followed by an 8-h nocturnal sleep episode at habitual bedtimes. Thereafter, volunteers either woke up to static light or to a dynamic light that changed spectrum and intensity across the scheduled 16-h waking day. Following an 8-h nocturnal sleep episode, the volunteers spent another 11 hours either under static or dynamic light. Static light attenuated the evening rise in melatonin levels more compared to dynamic light as indexed by a significant reduction in the melatonin AUC prior to bedtime during static light only. Participants felt less vigilant in the evening during dynamic light. After dynamic light, sleep latency was significantly shorter in both the baseline and treatment night while sleep structure, sleep quality, cognitive performance, and visual comfort did not significantly differ. The study shows that dynamic changes in spectrum and intensity of light promote melatonin secretion and sleep initiation in healthy men.

Current Insights into Optimal Lighting for Promoting Sleep and Circadian Health: Brighter Days and the Importance of Sunlight in the Built Environment

“…10,112 When measured across a divergent series of real-world or in-lab conditions, sparser patterns of ambient illumination (with lower zeitgeber strength) during the day also associate with later sleep initiation, less sleep pressure/slow-wave-sleep buildup under states of rest or sleep deprivation, more nighttime awakenings, worse perceptions of sleep quality, less circadian-robust sleep cycles, and increases in reported insomnia symptoms. [113][114][115][116][117][118][119][120][121][122][123][124][125][126] These results are consistent with seasonally oriented studies of participants stationed in Antarctica that quantified (1) more light-induced https://doi.org/10.2147/NSS.S251712…”

Should We Re-think Regulations and Standards for Lighting at Workplaces? A Practice Review on Existing Lighting Recommendations

“…Under strictly controlled laboratory conditions, we examined whether dynamic light across the day influences cognitive performance, visual comfort, melatonin secretion, sleepiness, and sleep ( 67 ). Volunteers either woke up with static daylight LED (100 lx at the pillow and 4000 K, melEDI 69 lx) or with a dynamic daylight LED that changed CCT (2700–5000 K) and intensity (0–100 lx at the pillow, melEDI 0.4–76 lx) across the day (daylight here refers to the spectral characteristics of the Toshiba TRI-R LED).…”

Melanopic Limits of Metamer Spectral Optimisation in Multi-Channel Smart Lighting Systems

“…Recent studies revealed that through an optimised smart lighting system energy costs of 17 to 60% [7] can be saved compared to traditional static lighting solutions [7,10,11]. Besides the aspect of saving energy, research is focusing on the implementation of dynamic patterns of light exposure [12], which vary the illumination or the correlated colour temperature (CCT) to support the circadian rhythm [13] or task-related performance [12]. The discovery of intrinsically photosensitive ganglion cells (ipRGCs) [14][15][16][17][18] made clear that besides the image-forming properties of colour and brightness perception [19], the composition of a light spectrum [20] can also affect the human alertness and cognitive performance [6,[21][22][23].…”