Why does morning sunlight improve sleep?
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Morning sunlight plays a crucial role in improving sleep quality and overall circadian rhythm. When you expose your eyes to sunlight in the morning, it serves as a powerful stimulus for your body's physiological systems, particularly setting your internal clock, which has a profound impact on sleep and wakefulness patterns.
Here are some of the key benefits of morning sunlight as outlined by :
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Regulates Cortisol Levels: Exposure to bright sunlight in the morning increases the amplitude of the morning cortisol spike by as much as 50%. This is beneficial because cortisol should be highest in the morning to enhance mood, focus, and alertness during the day, while lower levels in the evening facilitate better sleep 1.
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Sets Circadian Rhythms: Sunlight in the morning helps set the circadian clock by signaling the brain what time of day it is, which helps regulate the sleep-wake cycle. This is achieved through non-image forming cells in the eyes that are sensitive to bright light for setting biological rhythms 1 2.
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Suppresses Melatonin: Morning light helps suppress melatonin, the hormone that promotes sleepiness, thus fully awakening the system and maintaining alertness throughout the day 3.
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Improves Metabolic Health: Regular exposure to morning sunlight not only benefits sleep but also has positive effects on metabolism, likely due to improved sleep quality rather than a direct effect of light itself 4.
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Enhances Overall Well-being: It improves mental and physical health by increasing alertness, reducing anxiety, and even decreasing symptoms of depression, making it a simple, no-cost intervention for better sleep health 5.
By prioritizing time outdoors in the morning, ideally between sunrise and a few hours after, these benefits can be maximized, thereby positively impacting sleep and overall health.
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