Is there any difference between morning and evening sun rays on health grounds.A scientific explanation please.?
Yes, there are some differences between morning and evening sun rays on health grounds, primarily due to the differences in the intensity and composition of sunlight at those times of the day.
1. Intensity of UV radiation: The sun emits ultraviolet (UV) radiation, which is essential for the synthesis of vitamin D in the skin. However, excessive exposure to UV radiation can cause damage to the skin and DNA, leading to skin cancer and other health issues. The intensity of UV radiation is generally higher during the middle of the day, around noon, compared to the morning or evening. This is because the sun is at its highest point in the sky during this time, exposing the earth to more direct and concentrated sunlight. Therefore, it is recommended to limit sun exposure during the peak hours of the day, especially for individuals with sensitive skin or a history of sunburn.
2. UV spectrum composition: The UV spectrum of sunlight varies throughout the day. Morning sunlight has a higher proportion of UVA rays compared to UVB rays, while evening sunlight has a higher proportion of UVB rays. UVA rays have a longer wavelength and can penetrate the skin more deeply, reaching the dermis layer. They are associated with skin aging, wrinkles, and collagen damage. UVB rays have a shorter wavelength and are more likely to be absorbed by the outermost layer of the skin (epidermis). They are responsible for sunburn, skin reddening, and DNA damage, which can increase the risk of skin cancer. Therefore, it is important to protect the skin from both UVA and UVB rays, regardless of the time of the day.
3. Circadian rhythm: Morning sunlight can help regulate the body's circadian rhythm, which is the natural sleep-wake cycle. Exposure to bright light in the morning can help synchronize the body's internal clock with the external environment, improving sleep quality and overall well-being. On the other hand, exposure to bright light in the evening, especially close to bedtime, can disrupt the production of melatonin, a hormone that promotes sleepiness. This can make it harder to fall asleep and maintain good sleep quality.
It is important to note that while morning sunlight can provide some benefits, it is still essential to practice sun safety measures. This includes using sunscreen, wearing protective clothing, seeking shade, and avoiding excessive sun exposure, regardless of the time of day.
In summary, the differences between morning and evening sun rays on health grounds primarily relate to the intensity of UV radiation, the composition of the UV spectrum, and the impact on the body's circadian rhythm. Proper sun protection and awareness of the potential health risks associated with sunlight exposure are crucial for maintaining good health and preventing adverse effects.