Market regulators are investigating whether Tesla CEO Elon Musk and his brother violated insider trading rules in connection with whopping share sales in 2021, according to a report. The SEC launched its probe after Kimbal Musk sold $108 million in Tesla stock last year, just a day before a significant drop in the electric vehicle maker's share price. Tesla's stock value fell sharply after Elon Musk posted a Twitter poll asking whether he should sell 10% of his stake in the company.

FIND OUT HOW ELON MUSK IS RESPONDING TO THE PROBE

The US only needs to look north for new ways to generate tax revenue. With the legalization of recreational marijuana in October 2018, Canada has seen a $43.5 billion boost to its GDP. Although some US states already benefit from legal marijuana sales, one report estimated that cannabis revenue in the U.S. would total $45 billion in 2025 if marijuana were to be legalized at the federal level this year.

SEE WHY CANADA SERVES AS A GOOD MODEL FOR THE US

Researchers believe they have cracked the code on the age-old question about why it's harder to get a good night's sleep as we age. A new study claims to have identified "hyperexcitable neurons" that increase in activity over time, shedding light on the mystery of sleep.

SEE HOW THE PROBLEM ALSO PERSISTS IN OTHER SPECIES

What is the world record for the longest time period without sleep?

Thursday's answer: German immigrant Charles Feltman opened the first known U.S. hot dog stand at Coney Island, N.Y., around 1870.