Key result
Bright morning light exposure (2500 lx) significantly increased high-frequency power at night compared to general lighting (Roy's largest root = 1.62; p < 0.001) in elderly women with dementia.
Why the study?
The impact of bright morning light exposure on nighttime autonomic nervous system activity remains unclear.
Does bright morning light exposure enhance parasympathetic activity at night in elderly female patients with dementia?
Does bright morning light exposure enhance parasympathetic activity at night in elderly female patients with dementia?
Effect estimate: Roy's largest root 1.62
p-value: p=<0.001
Bright morning light therapy may enhance nocturnal parasympathetic activity and improve cognitive function in elderly women with dementia.
May support morning light for nocturnal parasympathetic activity in dementia; hypothesis-generating pending randomized confirmation of clinical benefit.
Exposure to bright morning light (BML) entrains the master circadian clock, modulates physiological circadian rhythms, and reduces sleep–wake disturbances. However, its impact on the autonomic nervous system at night remains unclear. Here, we investigated the effects of BML exposure on parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS) activity at night in elderly women. This nonrandomized controlled pilot study included female participants aged ≥ 60 years who were diagnosed with a type of dementia or cognitive disorder, excluding individuals with pacemakers. The treatment group was exposed to 2500 lx of BML, whereas the control group was exposed to 200 lx of general lighting. We measured heart rate variability to quantify ANS activity. The treatment group displayed significant increases in high-frequency (HF) power (Roy’s largest root = 1.62; p < 0.001) and nonsignificant decreases in normalized low-frequency (LF%) power. The corresponding nonsignificant decreases in the low-frequency/high-frequency (LF/HF) ratio and cognitive function were correlated with PSNS activity (Roy’s largest root = 1.41; p < 0.001), which improved severe dementia. BML exposure reduced SNS activity and enhanced PSNS activity at night in female participants, which improved cognitive function. Thus, BML therapy may be a useful clinical tool for alleviating cognitive decline.
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Liu et al. (2023) studied Dementia or cognitive disorder. Bright morning light (BML) vs. 200 lx of general lighting was evaluated on High-frequency (HF) power (parasympathetic nervous system activity) (Roy's largest root 1.62, p=<0.001). Bright morning light exposure (2500 lx) significantly increased high-frequency power at night compared to general lighting (Roy's largest root = 1.62; p < 0.001) in elderly women with dementia.
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