The summer solstice, the longest day of the year in the Northern Hemisphere, occurs on Sunday (June 20) at 11:32 pm EDT (Monday, June 21, 03:32 UTC).This event occurs when Of earth The tilt to the sun is maximum, with the sun pointing directly above the tropics of cancer.
In other words, today is the most sunny day in the Northern Hemisphere. That long sunlight can make it difficult for people in north latitude to know when to sleep without looking at the clock, but the midnight sun is not a problem for many other animals.
On this day, we will provide more than 24 hours of sunlight. Arctic, North latitude people are celebrating with special events such as: Live broadcast The moment the solstice begins in England Stonehenge.. But without a clock, people can ignore bedtime because humans are terrible at telling time during periods of almost bright or almost dark. 1974 study It is published in The Journal of Physiology. This is because light has a great influence on the circadian rhythm of the human body, that is, the cycle of sleep and wakefulness.
However, Corey Williams, a biologist at the University of Alaska Fairbanks, said that many animals in northern latitudes can naturally control their sleep and wake cycles in extreme sunlight conditions.
“Some animals stop sleeping for long periods of time,” Williams told Live Science. For example, Semi Palm Sand Piper (Calidris pusilla) — Small, brown and white Shigichidori Breed over the Arctic — don’t suffer from long-term sunlight. They spend all day sleeping and awakening, alternating with their nesting companions. “When the male is active, the female is in the nest, and vice versa,” Williams said. “It’s not a 24-hour schedule.”
reindeer Also, ignore the lack of light-dark cycles during the summer. Instead, their sleep cycle is dominated by ultradian rhythms. That is, you sleep whenever you need to digest food. “They lose their normal long sleep,” Williams said. “They take a lot of naps during the day instead of intensive sleep.
According to Williams, this only happens with polar species. Because those actions do not go through a cycle of light and dark. At this time of the year, the advantage of animals being active at specific times is lost. For example, nighttime foraging is always sunlight, so it does not save energy or provide protection from predators.
However, not all polar species abandon circadian rhythms. For example Arctic ground squirrel (((Spermophilus parryii). Stick to their sleep schedule all year round. According to Williams, they retreat into burrows to save energy during the darkest hours of summer (not so dark yet, like dusk).
Scientists such as Williams are still working to figure out what’s different about polar bears that maintain their sleep rhythms.On average The temperature of the earth rises“As animals move to higher latitudes, it would be interesting to see how animals that are not exposed to polar conditions react when they move north,” Williams said.
Editor’s Note: This story was published on June 21, 2018 and updated today with information for 2021.
Originally published Live science..
How does the summer solstice affect animals?
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