Why do we lose days when calendars change? How did ancient Romans accidentally mess up leap years for decades? And what exactly is a leap second?

As we approach another New Year, join Deb for a gentle journey through humanity's long quest to organize time. From the ancient Egyptians' beautifully simple 365-day calendar to the Mayans' multiple overlapping systems, from Julius Caesar's elegant reform to Pope Gregory's controversial fix that made ten days vanish from history.

Discover why September is the ninth month when "septem" means seven, how the Islamic calendar cycles through all the seasons, and why computer programmers have nightmares about leap seconds. Learn about the Hebrew calendar's intricate 19-year cycle, Ethiopia's calendar that's 7-8 years "behind" ours, and Samoa's decision to simply skip December 30, 2011.

We'll explore the surprisingly complicated calculation of Easter's date, the Y2K bug that wasn't quite as overblown as people thought, and why Britain rioted (maybe) when they lost eleven days in 1752. Plus: calendar reform proposals that would give us identical quarters or 13-month years, and why we'll probably never adopt them.

Perfect bedtime learning about the systems that structure our lives—delivered in Dormant Knowledge's signature relaxing style.

Topics covered:

• Egyptian, Babylonian, Mayan, Chinese, and Roman calendar systems
• Why our month names don't match their numbers
• Julius Caesar's reform and the Julian calendar
• The Gregorian calendar reform of 1582
• Islamic, Hebrew, Persian, and Ethiopian calendars still in use today
• The complicated rules of leap years (and why 2000 was special)
• Leap seconds and why they crash computer systems
• The International Date Line and its quirks
• Failed calendar reform proposals throughout history

Whether you drift off after ten minutes or stay awake through the whole episode, you'll come away with a deeper appreciation for the intricate systems humans have created to measure our journey through time.

Dormant Knowledge is the educational sleep podcast for curious minds. Learn something fascinating while you fall asleep.

Journey through humanity's oldest celebration as we explore winter solstice traditions from around the world. In this peaceful episode perfect for falling asleep, discover how ancient cultures marked the longest night of the year—and why their rituals still resonate today.

What is the winter solstice? It's that precise astronomical moment when the Northern Hemisphere tilts furthest from the sun, giving us our longest night and shortest day. But for thousands of years, it's meant so much more than just a date on the calendar. It's been a time of hope, celebration, and the promise that light will return.

We'll visit the 5,000-year-old passage tomb at Newgrange in Ireland, where the rising sun illuminates a dark chamber for just 17 minutes on solstice morning. We'll explore Stonehenge and the evidence of massive midwinter feasts held 4,500 years ago. We'll discover how the Germanic peoples celebrated Yule with evergreens and Yule logs—traditions that survive in modern Christmas celebrations.

Travel to ancient Rome for Saturnalia, when social rules were turned upside down and masters served their slaves. Experience the Persian festival of Yalda, where families gather to read poetry and eat pomegranates through the longest night. Learn about Chinese Dongzhi, when families reunite to make and share tangyuan dumplings, and Japanese Toji, where people soak in yuzu-scented baths for good health.

Along the way, we'll explore why humans across vastly different cultures developed remarkably similar responses to this astronomical event: lighting fires, decorating with evergreens, feasting together, and creating rituals around the return of light. We'll discover how many Christmas traditions—from decorated trees to gift-giving to festive meals—have their roots in ancient solstice celebrations.

This episode is designed to be both genuinely educational and deeply relaxing. Whether you listen all the way through or drift off somewhere in the middle, you'll absorb fascinating stories about how our ancestors understood the cosmos, marked time, and found hope in the darkest season.

Perfect for curious minds who want to learn while falling asleep.

Episode Length: ~49 minutes
Topics: Winter solstice, ancient astronomy, cultural traditions, Yule, Saturnalia, Newgrange, Stonehenge, seasonal celebrations, history of Christmas

Find more episodes at dormantknowledge.comFollow us: @dormantknowledge (Instagram/Facebook) | @drmnt_knowledge (X)

Ever wondered about those massive concrete structures where highways loop, merge, and stack on top of each other? Tonight, we're exploring the surprisingly fascinating world of highway interchanges—the engineering marvels you've driven through hundreds of times without a second thought.

Discover the elegant cloverleaf designs of the 1920s, the towering five-level stacks of modern cities, and the innovative diverging diamond interchanges that briefly move you to the "wrong" side of the road. Learn why early traffic engineers faced a critical problem: how to let high-speed traffic cross paths without anyone stopping, and why their solutions—from New Jersey's pioneering cloverleafs to Los Angeles's billion-dollar spaghetti junctions—shaped American cities and suburbs.

We'll explore the "weaving problem" that plagued early designs, the controversial legacy of builder Robert Moses, and what the future holds for these monuments to automobile culture in an era of autonomous vehicles and changing transportation priorities.

Perfect for curious minds who love learning about the hidden complexity of everyday infrastructure. Settle in and drift off as we unravel the loops, levels, and logic of highway interchanges.

Dormant Knowledge is the educational sleep podcast for curious minds. Learn something fascinating while you fall asleep.

Visit dormantknowledge.com | Follow @dormantknowledge (Instagram/Facebook) or @drmnt_knowledge (X)