Dim light at night prior to adolescence increases adult anxiety-like behaviors

Abstract

Dim light at night (dLAN) disrupts circadian organization and influences adult behavior. We examined early dLAN exposure on adult affective responses. Beginning 3 (juvenile) or 5 weeks (adolescent) of age, mice were maintained in standard light-dark cycles or exposed to nightly dLAN (5 lux) for 5 weeks, then anxiety-like and fear responses were assessed. Hypothalami were collected around the clock to assess core clock genes. Exposure to dLAN at either age increased anxiety-like responses in adults. Clock and Rev-ERB expression were altered by exposure to dLAN. In contrast to adults, dLAN exposure during early life increases anxiety and fear behavior.

Circadian rhythm disruption and mental health

“…However, the effects of light as a circadian disruptor are inconsistent across species [104][105][106][107][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 intensity 108,109 . For example, exposure to dim light at night during early development in mice increases adult anxietylike responses 108,109 , whereas exposure of adult mice to light at night reduces anxiety-like responses 106 .…”

“…halogen, compact fluorescent, or light emitting diode) and its intensity 108,109 . For example, exposure to dim light at night during early development in mice increases adult anxietylike responses 108,109 , whereas exposure of adult mice to light at night reduces anxiety-like responses 106 . Furthermore, glucocorticoid concentrations are often reduced in hamsters and unaltered in mice exposed to light at night compared to dark nights, suggesting that the affective behavioral responses to atypical lighting are not the result of elevated corticosterone 60,110,111 .…”

Dim Light at Night and Constant Darkness: Two Frequently Used Lighting Conditions That Jeopardize the Health and Well-being of Laboratory Rodents

“…At 5 lux, DWL N reduced post-weaning growth rates and had long-lasting effects by increasing anxiety-like and fear-like behavior and the fearful responses to foot-shock in adults that had been exposed pre-and/or post-natally ( 111 , 116 ). According to the period of exposure during rearing, the metabolic functions during adulthood are affected differently by DWL N .…”

“…These development-dependent alterations in metabolic energy homeostasis were associated with the disruption of circadian expression in crucial components of the molecular circadian clock in both the SCN and peripheral tissues that regulate metabolic functions. In particular, post-weaning exposure beginning at the juvenile or adolescent stage increases and decreases the amplitude of daily rhythm in the hypothalamic Clock and the expression of Rev-ERB in adulthood, respectively ( 111 ). However, during adulthood, DWL N attenuates the rhythmic expression of the core circadian clock genes Per1 Per2, Cry1 , and Cry2 and PER1 and PER2 in the SCN, along with Bmal1, Per1, Per2, Cry1, and Cry2 and Rev-ERB in the liver and adipose tissue ( 119 ).…”

Disruption of Circadian Rhythms by Light During Day and Night

“…(54) This increase in sensitivity to light combined with increasing use of self-luminous displays in the evening may have long-term consequences, given that early-life environmental exposures may affect behavior and physiology in adulthood. (55)…”