Dim light at night impairs recovery from global cerebral ischemia

Abstract

Nighttime lighting is one of the great conveniences of modernization; however, there is mounting evidence that inopportune light exposure can disrupt physiological and behavioral functions. Hospital patients may be particularly vulnerable to the consequences of light at night due to their compromised physiological state. Cardiac arrest/cardiopulmonary resuscitation (CA) was used to test the hypothesis in mice that exposure to dim light at night impairs central nervous system (CNS) recovery from a major pathological insult. Mice exposed to dim light at night (5 lux) had higher mortality in the week following cardiac arrest compared to mice housed in dark nights (0 lux). Neuronal damage was significantly greater in surviving mice exposed to dim light at night after CA versus those housed in dark nights. Dim light at night may have elevated neuronal damage by amplifying pro-inflammatory pathways in the CNS; Iba1 immunoreactivity (an indication of microglia activation) and pro-inflammatory cytokine expression were elevated in mice exposed to dim light at night post-CA. Furthermore, selective inhibition of IL-1β or TNFα ameliorated damage in mice exposed to dim light at night. The effects of light at night on CA outcomes were also prevented by using a wavelength of nighttime light that has minimal impact on the endogenous circadian clock, suggesting that replacing broad-spectrum nighttime light with specific circadian-inert wavelengths could be protective. Together, these data indicate that exposure to dim light at night after global cerebral ischemia increases neuroinflammation, in turn exacerbating neurological damage and potential for mortality.

Dim light at night exacerbates stroke outcome

“…Indeed, many of the negative consequences of the ICU for health outcomes have historically been attributed to disrupted sleep. Our studies of nocturnal mice (that typically sleep during the light phase) demonstrate that although sleep is a highly salient output of circadian clocks, disruption of the central circadian clockwork is sufficient to produce poor outcomes (Alibhai et al., 2014; Fonken et al., 2019; Penev et al., 1998). Further, we have previously shown that sleep is not disrupted by dim light at night in house mice (Borniger, Weil, Zhang, & Nelson, 2013) indicating that sleep disruption is unlikely to drive the current phenomenon.…”

“…Indeed, the survival of penumbral tissue is a determinant of long‐term functional outcomes and supporting the survival of those cells is a major goal of ischaemia research (Rogers, Campbell, Stretton, & Mackay, 1997). Recently, we reported that artificial dim light at night exacerbates the cell death and inflammatory responses to cardiac arrest and cardiopulmonary resuscitation, a global ischaemic injury (Fonken et al., 2019). Here, we hypothesized that exposure to dim white light, at night during the period after experimental focal ischaemic stroke would increase infarct size, exacerbate inflammatory responses and impair functional outcomes compared to animals housed in dark night conditions.…”

Dim Light at Night Induced Neurodegeneration and Ameliorative Effect of Curcumin

“…However, people are gradually realizing the ill effects of night-time light exposure and considering it as an environmental perturbation [ 5 , 6 ]. Recent studies have indicated that alteration of daily light dark cycle contributes to the development of many pathophysiological conditions such as cardiovascular disease [ 7 , 8 ], metabolic syndrome [ 9 , 10 ], sleep disorders [ 11 ], aging [ 12 ], neurodegenerative disorders [ 13 , 14 , 15 ], mood disorders [ 16 ], and cognitive impairment [ 17 ]. Exposure to artificial lighting during the night (dim light at night (dLAN)) and shift working are reported to interfere with proper physiological functioning of the brain and body [ 18 , 19 , 20 , 21 ].…”

Dim Light at Night Disturbs Molecular Pathways of Lipid Metabolism

“…Circadian disruption in response to diverse environmental or endogenous perturbations can misalign metabolic homeostasis and thereby contribute to the development of metabolic disorders [ 18 , 19 , 20 ]. Accordingly, a growing number of epidemiological and experimental studies have reported an association between dLAN exposure and metabolic dysfunction, leading to an increased risk of obesity [ 21 , 22 ], type 2 diabetes mellitus [ 23 ], and cardiovascular disease [ 24 , 25 ]. Experiments in mice showed that dLAN (5 lx) exposure resulted in an impaired glucose tolerance and increased body mass, likely due to shifting the rhythm of food intake into daytime [ 26 ].…”