Topic
Light Cycle
About: Light Cycle is a research topic. Over the lifetime, 223 publications have been published within this topic receiving 6449 citations.
Papers published on a yearly basis
1 / 2
Papers
TL;DR: It is shown, using an aberrant light cycle that neither changes the amount and architecture of sleep nor causes changes in the circadian timing system, that light directly regulates mood-related behaviours and cognitive functions in mice.
Abstract: The daily solar cycle allows organisms to synchronize their circadian rhythms and sleep-wake cycles to the correct temporal niche. Changes in day-length, shift-work, and transmeridian travel lead to mood alterations and cognitive function deficits. Sleep deprivation and circadian disruption underlie mood and cognitive disorders associated with irregular light schedules. Whether irregular light schedules directly affect mood and cognitive functions in the context of normal sleep and circadian rhythms remains unclear. Here we show, using an aberrant light cycle that neither changes the amount and architecture of sleep nor causes changes in the circadian timing system, that light directly regulates mood-related behaviours and cognitive functions in mice. Animals exposed to the aberrant light cycle maintain daily corticosterone rhythms, but the overall levels of corticosterone are increased. Despite normal circadian and sleep structures, these animals show increased depression-like behaviours and impaired hippocampal long-term potentiation and learning. Administration of the antidepressant drugs fluoxetine or desipramine restores learning in mice exposed to the aberrant light cycle, suggesting that the mood deficit precedes the learning impairments. To determine the retinal circuits underlying this impairment of mood and learning, we examined the behavioural consequences of this light cycle in animals that lack intrinsically photosensitive retinal ganglion cells. In these animals, the aberrant light cycle does not impair mood and learning, despite the presence of the conventional retinal ganglion cells and the ability of these animals to detect light for image formation. These findings demonstrate the ability of light to influence cognitive and mood functions directly through intrinsically photosensitive retinal ganglion cells.
524 citations
Journal Article•
TL;DR: Rod outer segment disc shedding in the rat can be considered to follow a circadian rhythm because it is a self-sustaining oscillation; it appears to free-run with a period close to 24 hr in the absence of lighting cues; and it can re-entrain to shifts in the light cycle.
Abstract: Rod outer segment disc shedding has been examined in the rat to determine whether it follows a circadian rhythm. The burst of shedding that occurs soon after the onset of light repeats daily in continuous darkness for at least 12 days. The disc shedding rhythm becomes slightly longer than 24 hr in continuous darkness, with an estimated period of 24 hr and 8 min to 24 hr and 19 min. In rats maintained in cyclic light, the disc shedding rhythm can be re-entrained to a new light schedule following a phase shift in the environmental lighting. After a 3 hr phase delay, at least 4 weeks is required for re-entrainment. Rod outer segment disc shedding in the rat can be considered to follow a circadian rhythm because (1) it is a self-sustaining oscillation; (2) it appears to free-run with a period close to 24 hr in the absence of lighting cues; and (3) it can re-entrain to shifts in the light cycle.
234 citations
Journal Article•
TL;DR: Available evidence suggests that at least some of the chemical activities of the visual cells and pigment epithelium oscillate with a daily rhythm, which is synchronized with the daily fluctuation of light in the environment.
Abstract: Newly hatched chickens were maintained on a daily light cycle of 12 hr of light and 12 hr of darkness for 12 days. The pigment epithelium was then examined by electron microscopy at different times of day. Shortly after the beginning of the light period, the rods discarded groups of outer segment membranes. During the remainder of the light period, the membranes were degraded by the pigment epithelium. Early in the dark period, the cones shed membranes, which were digested by the pigment epithelial cells during the subsequent hours of darkness. Available evidence suggests that at least some of the chemical activities of the visual cells and pigment epithelium oscillate with a daily rhythm, which is synchronized with the daily fluctuation of light in the environment.
225 citations
TL;DR: Zebrafish locomotor activity is regulated by a circadian clock that is temperature compensated, and rhythmicity is most robust at 21 degrees C, this would be the optimal temperature for future studies of the physiological basis of zebrafish behavioral rhythms.
180 citations
TL;DR: The influences of light on human health is explored and it is suggested that exposure to artificial light may have harmful effects and health considerations should be incorporated into the design of light environments.
Abstract: This article explores the influences of light on human health and suggests that exposure to artificial light may have harmful effects. The effects of ligght on mammalian tissue are either direct or indirect depending on whether the immediate cause is a photochemical reaction within the tissue or a neural or neuroendocrine signal generated by a photoreceptor cell. Light exerts an indirect effect on the ovaries of rats and this effect is mediated by photoceptive cells in the retina. The light cycles involved in night and day and changing day lenght appear to be associated with rhythmic changes in mammalian biological functions such as body temperature. Light levels and rhythms also influence the maturation and subsequent cyclic activity in the gonads of mammals with the particular response seemingly dependent on whether the species ovulated once a year or at regular intervals. Ovulation can be accelerated in diurnally active monestrous animals by exposing them to artificially long days. Pineal activity in rats can be suppressed by exposing the animals continuously to light. Such findings on the multiple and disparate effects of light suggest the view that health considerations should be incorporated into the design of light environments. The illumination provided by artificial indoor lighting is often less than 10% of the light normally available outdoors. It is urged that decisions on lighting be based on knowledge of mans biological needs as well as economic and technoloical considerations.
179 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 2 |
| 2024 | 2 |
| 2023 | 7 |
| 2022 | 13 |
| 2021 | 5 |
| 2020 | 5 |