Recent research has uncovered that exposure to greater levels of light leads to enhanced levels of concentration and heightened awareness.mination, which supports a. theory that light therapy treatments can improve sleep quality and daily activity; however, the study argued more needs to be done to understand how these treatments affect the hypothalamus in the brain and the behavior of light in relation to different structures in the brain.
The exposure to brighter light is believed to enhance memory activity and cognitive function, most likely due to changes in the hypothalamus, according to new research.
The editors of eLife magazine lauded the study's fundamental significance, stating that it is a significant contribution to our understanding of how different light levels affect human behavior. The study's robustness supports the authors' analyses of the intricate interplay between light exposure, hypothalamic activity, and cognitive function.
The results could be used in light therapy to inform other treatments that aim to improve the sleep quality and affective state of individuals, while also promoting improved attention and task performance.
In recent years, there has been extensive research on the biological effects of light exposure. More illumination has been shown to be associated with heightened alertness and increased cognitive performance. These effects are mainly caused by ipRCGs, light-sensitive cells that project to different areas of the brain. These cells are most prevalently located within the hypothalamus, which is typically involved in regulating circadian rhythms, sleep and alertness, and cognitive functions. Nevertheless, this understanding of the brain circuitry underlying these biological effects of light has almost exclusively developed from studies in animals.
Islay Campbell, the lead author, explains that it is difficult to convey findings about how light exposure affects the brain in animal models to humans due to the later maturation of the cortex in humans, which enables more complex cognitive processing.
To investigate the influence of light on human cognition, Campbell and his team recruited 26 young adults and asked them to complete two auditory cognitive tasks. They asked participants to complete an executive task that differed from the ‘n-back task’ by determining if a current sound was identical to the one they heard earlier. Additionally, they also asked participants to identify the gender of a voice that was pronounced in a neutral tone or in an angry tone. Participants were placed in darkness or exposed to four levels of light while performing the tasks.
The posterior hypothalamus exhibited increased activity during both tasks with increased light, while the inferior and anterior hypothalamus showed reduced activity under higher light levels.
The team aimed to determine if the alterations in regional hypothalamus were 101db or 91db in cognitive performance, and aimed to assess if the cognitive performance of the participants (due to their higher level of cognition) was influenced by higher levels of light. The findings indicated that the increase in cognitive performance under higher illuminance was associated with better performance by participants, but it was unexpected that the increase in cognitive performance was not directly mediated by the activity of the posterior hypothalamus.
Conversely, the posterior hypothalamus' activity may be more correlated with behavior during an emotional task, indicating a potential context-dependent relationship between cognition and posterior hypothalamus activity.
The authors recommend further investigations into the effects of light on other structures or brain networks to determine how different light levels influence their crosstalk and interactions with the cortex and thereby induce behavioral modifications.
Campbell emphasizes the significance of answering the questions from their study as implementing light-based methods to alleviate daytime fatigue, improve cognitive impairments, and promote restfulness with minimal cost and unwanted side effects.
According to Gilles Vandewalle, a senior author, the findings suggest that the human hypothalamus does not respond uniformly to varying light levels during cognitive tasks. The study highlights that the posterior hypothalamus is responsible for achieving this stimulating effect, in addition to the decreased activity of the anterior and inferior hypothalamus, as well as other brain structures that regulate wakefulness.
The study led by Campbell suggests that targeting lighting for therapeutic purposes is exciting, but understanding its impact on the brain is more complex. This study sheds light on the hypothalamus, as it has a significant impact on the cortex.
A scholarly contribution to the study of the regional response to light illuminance in the human hypothalamus has been published as a draft paper in eLife on 23 April 2024. The DOI for this publication is 10.7554/ETCW.26576.1.
