Why July 1 is an important day in history ... your sleep habits may be genetic ... plus more

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We hope this week's newsletter finds you enjoying a restful summer break. In this edition, we learn why our sleeping habits may be determined by our DNA. But first, as many Americans are getting ready to celebrate the upcoming Fourth of July holiday, today -- the first day of July -- is also an important milestone in American history:

50 years ago today, 18-year-olds were allowed to vote in the US

Today marks the 50th anniversary of the 26th Amendment, which lowered the voting age from 21 to 18. There is an interesting history lesson behind why the US Constitution was changed, and it has to do with the Vietnam War:

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Why we sleep the way we do

Are you a night owl or an early bird? Researchers have found that our genetics may actually regulate how and when we sleep. Their study centered around people who fall asleep by 7 p.m., no matter how hard they tried to stay awake, and get up extremely early, say by 2 a.m. or 3 a.m.

Find out why

Meet the latest addition to the human family tree

The so-called dragon man -- named after China's Black Dragon River -- likely belonged to a lineage that may be more closely related to modern-day humans than Neanderthals, a recent study found. The study is centered around a skull fragment, found in a cold region of China, that dates as far back as 309,000 years. One of the study's coauthors said the skull "is the most important fossil I've seen in 50 years."

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Supreme Court sides with cheerleader who cursed online

What is a school allowed to do when its students' social media posts violate school policies? The US Supreme Court recently ruled in favor of Brandi Levy, who was suspended from cheerleading four years ago at her Mahanoy City, Pennsylvania high school because of her profanity-laced Snapchat post. The high court's ruling will have wide implications for the free speech rights of some 50 million public school children and school districts across the country that are having to deal with off-campus and online speech that could amount to bullying or threats.