Chronic Light Exposure in the Middle of the Night Disturbs the Circadian System and Emotional Regulation
Open accessAbstract
In mammals, the circadian system is composed of a principal circadian oscillator located in the suprachiasmatic nucleus (SCN) and a number of subordinate oscillators in extra-SCN brain regions and peripheral tissues/organs. However, how the time-keeping functions of this multiple oscillator circuit are affected by aberrant lighting environments remains largely unknown. In the present study, we investigated the effects of chronic light exposure in the middle of the night on the circadian system by comparing the mice housed in a 12:4:4:4-h L:DLD condition with the controls in 12:12-h L:D condition. Daily rhythms in locomotor activity were analyzed and the expression patterns of protein products of clock genes Period1 and Period2 (PER1 and PER2) were examined in the SCN and extra-SCN brain regions, including the dorsal striatum, hippocampus, paraventricular nucleus (PVN), and basolateral amygdala (BLA). Following 2 weeks of housing in the L:DLD condition, animals showed disturbed daily rhythms in locomotor activity and lacked daily rhythms of PER1 and PER2 in the SCN. In the extra-SCN brain regions, the PER1 and PER2 rhythms were affected in a region-specific pattern, such that they were relatively undisturbed in the striatum and hippocampus, phase-shifted in the BLA, and abolished in the PVN. In addition, mice in the L:DLD condition showed increased anxiety-like behaviors and reduced brain-derived neurotropic factor messenger RNA expression in the hippocampus, amygdala, and medial prefrontal cortex, which are brain regions that are involved in emotional regulation. These results indicate that nighttime light exposure leads to circadian disturbances not only by abolishing the circadian rhythms in the SCN but also by inducing misalignment among brain oscillators and negatively affects emotional processing. These observations serve to identify risks associated with decisions regarding lifestyle in our modern society.
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The effects of light as a circadian disruptor are inconsistent across species and may depend on the developmental window during which circadian disruption occurs, as well as the type of light and its intensity.
“However, the effects of light as a circadian disruptor are inconsistent across species104–108, and may depend on the developmental window during which circadian disruption occurs, as well as the type of light (i.e. halogen, compact fluorescent, or light emitting diode) and its intensity108,109.”
From Circadian rhythm disruption and mental health (2020) · cites this paper as [107]
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References 75 · Cited by 37
- Authors
- Ikeno, T., & Yan, L.
- Affiliations
- Michigan State University (US)
- Department of Psychology, Michigan State University, East Lansing, MI
- Corresponding author
- Ikeno, Tomoko
- ORCID
- Ikeno, Tomoko
- Venue
- Journal of Biological Rhythms
- Publisher
- SAGE Publications
- Published
- 2016-06-23
- Volume
- 31
- Issue
- 4
- Pages
- 352-364
- ISSN
- 0748-7304 (ISSN-L)
- 1552-4531
- OpenAlex
- W2341684324
- Cited by
- 37
- References
- 75
- Citations by year
- 2026: 3 · 2025: 5 · 2024: 5 · 2023: 2 · 2022: 2 · 2021: 2 · 2020: 11 · 2019: 3 · 2018: 1 · 2017: 3
- FWCI
- 1.48
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Journal of Biological Rhythms (publishedVersion)
- PubMed (publishedVersion)
- Topics
- Life Sciences › Neuroscience › Endocrine and Autonomic Systems › Circadian rhythm and melatonin
- Physical Sciences › Environmental Science › Global and Planetary Change › Impact of Light on Environment and Health
- Social Sciences › Psychology › Experimental and Cognitive Psychology › Sleep and Work-Related Fatigue
- Keywords
- nocturnal light exposure, circadian rhythm disruption, suprachiasmatic nucleus, clock genes, Per1, Period2, paraventricular nucleus, basolateral amygdala, hippocampus, dorsal striatum, locomotor activity rhythm, anxiety-like behavior, brain-derived neurotrophic factor, emotion regulation, artificial light at night
- MeSH terms
- Animals, Anxiety, Brain, Circadian Rhythm, Darkness, Emotions, Light, Paraventricular Hypothalamic Nucleus, RNA, Messenger, Sleep, Suprachiasmatic Nucleus, Brain-Derived Neurotrophic Factor, Mice, Period Circadian Proteins
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