Science Vs – The Full Moon: Is It Messing With Us?

Podcast: Science Vs (Spotify Studios)
Date: October 2, 2025
Host: Wendy Zuckerman
Theme: Investigating whether and how the full moon affects human behavior, physiology, and health—through science, not superstition.

Episode Overview

This episode dives into the longstanding belief that the full moon can influence our behavior, health, and even menstrual cycles. Host Wendy Zuckerman and senior producer Meryl Horne sift through folklore, popular stories, and the latest scientific evidence to uncover fact from fiction. They explore studies on ER visits, animal behavior, sleep cycles, and menstrual rhythms—and throw in some humor and candid listener anecdotes along the way.

Street Interviews: What Do People Say About the Full Moon?

[00:48–02:14]

• Common Beliefs:
  • “Makes people wild... carnal... There’s a carnal thing happening.” — New Yorkers in the park [00:48]
  • “I’m gonna stay in that night. I know I could feel weird or do crazy stuff.” — Park interviewee [01:09]
  • Some believe retail and healthcare workers have it worst during full moons: “I worked retail… every single time on the full moon, we had the craziest customers… It was the worst days.” [01:53]
• Menstrual Cycle Links:
  • “My period will probably be coming, because it’s usually cycled with the moon.” [02:34-02:35]
  • At a cosmetology school: “All their cycles synced up to… the full moon.” [02:37]

The Science: What Actually Happens During a Full Moon?

The Astronomy of the Full Moon

[05:10–06:52]

• Explanation: Meryl Horne uses a prop to explain full and new moons, comparing celestial bodies to sandwich ingredients: “The sun and the moon are making an Earth sandwich.” — Meryl [06:32]
• Skeptical Framing: “Could just the fact that the billiard balls up in space are in this arrangement affect our behavior?” — Wendy [06:52]

Animal Behavior & Lunar Effects

[07:04–08:40]

• New Moon: Coyotes and owls act up more; badgers mark more territory.
• Full Moon: Certain birds hatch more; worms do mating dances; corals spawn; nocturnal primates eat more; 1800s claim about monkeys being more fertile.

Quote: “I actually couldn’t find any evidence backing [wolves howling at the full moon] up at all.” — Meryl [07:13]
Quote: “Now we’re cooking with the rhesus monkeys.” — Wendy [08:40]

The Hospital Myth: Do ERs Get Busier?

[08:59–13:58]

• Historic Study: Dr. Wendy Coates, ER physician, conducted research on 1,400+ trauma cases, comparing nights around the full moon to other nights.
• Result: “It looks like there’s no difference.” — Dr. Wendy Coates [12:33]
• Surprising Finding: Potential for slightly fewer and less severe traumas on full moon nights, possibly due to increased brightness making dangerous behavior less likely.
• Global Research: Other studies (Netherlands, reviews) found no support for more ER activity or crime during full moons.

Quote: “There was no increase in how many people were admitted, how bad their traumas were, or how many died around the full moon.” — Meryl [12:37]

Why Do ER Myths Persist?

[14:48–15:45]

• Bonding Theory: Full moon shifts provide a rallying point: “We can’t predict how busy it’ll be, but what we can predict is we’re all there for each other… talking about a full moon gives you encouragement to help you do your job well.” — Dr. Coates [15:13]

What About Sleep? The Moon's Hidden Influence

[16:30–22:31]

Key Study: Indigenous & Urban Sleep Patterns

[16:35–22:31]

• Research by: Prof. Horacio de la Iglesia (University of Washington)
• Methods: Tracked sleep in indigenous communities without electricity and in urban settings.
• Findings:
  • In both low-light and city environments, people slept less and went to bed later in the days leading up to the full moon. The effect was ~45 minutes in rural settings, 20–40 minutes in Seattle.
  • This pattern held even when natural moonlight seemed unlikely to be the cause (e.g., Seattle winters).
• Visual Evidence: “You see people doing this beautiful sinusoidal oscillation in their sleep.” — Prof. de la Iglesia [21:07]
• Implication: Sleep cycles track the lunar cycle in a wave-like pattern, hinting at unknown mechanisms.

How Could the Moon Affect Us?

[26:09–34:34]

Theories Investigated

1. Gravitational Pull & Tides

• Public Belief: “We’re made of, like, 70% water… the moon controls the tides, so it makes sense it affects us.”
• Reality: Scientists say the gravitational pull on humans is minuscule—less than being near a tall building. “The case for gravity, I’d say, is pretty weak.” — Meryl [29:23]
• Expert Input: No known animal can directly sense the moon’s gravitational pull (beyond tidal effects). — Prof. Kristin Tessmar-Raible [29:18]

2. Magnetic Fields & Cryptochrome

• Earth's Magnetic Field: The moon subtly alters it as it orbits.
• Biological Evidence: Migratory birds and butterflies navigate using the magnetic field, via the protein cryptochrome.
• Humans: We have a similar protein. Recent data hints our sleep patterns could be subtly tied to lunar-induced magnetic changes, but “nobody’s connected all the dots.” — Meryl [32:52], [33:22]
• Speculation: This is “wild speculation… at the frontiers of our knowledge.” — Prof. Kristin Tessmar-Raible [33:17]
• Quote: “Just because it is a subconscious phenomenon, it doesn’t mean that it doesn’t exist… we usually don’t feel our liver, at least hopefully not. But it’s very existing.” — Prof. Tessmar-Raible [33:37]

Menstruation & The Moon: Myth or Fact?

[34:38–41:15]

Professor Charlotte Helfrich-Förster's Study

• Origin: She kept period records most of her life and noticed menses often started near the full moon.
• Data: She collected 15 years of data from herself and 21 other women.
• Result: In her small sample, menses were somewhat more likely around full or new moon.
• Magnitude: “The effect is really very small… only a small part during a cycle is synchronous to the moon.” — Prof. Helfrich-Förster [39:15]
• Expanded Study: With records from 100+ more people, the synchrony disappeared.
• Massive App Study: Analysis of 7.5 million cycles using period tracking apps found no moon-linked synchrony.
• Quote: “We are the anecdote in the room that gets the headlines.” — Wendy [40:17]
• Current View: Most people’s cycles aren’t synced to the moon, and any observed synchrony appears coincidental.

Host Reflections and Final Thoughts

[41:15–end]

• Wendy’s Take: “I love a big full moon. I like thinking how small I am in this big universe. I don’t know if it’s having some deeper subconscious effect on my body.” [41:45]
• Meryl’s Take: “Now I am less skeptical… There is an effect at least on our sleep that we don’t understand yet. I feel like I’m more humble now about what’s possible with our bodies and the moon.” [42:21]
• Notable Moment: Wendy and Meryl yipping like coyotes to close out [43:03].

Key Segment Timestamps

• Popular Beliefs/Street Interviews: [00:48–02:14]
• Moon Phases Explained: [05:10–06:52]
• Animal & Full Moon Behavior: [07:04–08:40]
• ER Studies (Dr. Wendy Coates): [08:59–13:58]
• Sleep Cycles & Lunar Patterns (Prof. Horacio de la Iglesia): [16:30–22:31]
• Gravity & Magnetic Fields Theories: [26:09–34:34]
• Menstruation Studies: [34:38–41:15]
• Host Conclusions & Meta-Discussion: [41:15–end]

Notable Quotes

• On ER Myths:
  “There was no increase in how many people were admitted, how bad their traumas were, or how many died around the full moon.” — Meryl [12:37]

• On Animal & Human Connection:
  “For me, as a biologist, humans are just another type of animal.” — Prof. Kristin Tessmar-Raible [34:11]

• On Wild Speculation:
  “This is a lot of wild speculation, I have to emphasize.” — Prof. Kristin Tessmar-Raible [33:17]

• On Host’s Change of Heart:
  “Now I am less skeptical… There is an effect at least on our sleep that we don’t understand yet.” — Meryl [42:21]

Science Vs’ Final Answer:

• No, the full moon doesn’t trigger more ER visits, crime spikes, or widespread menstrual synchrony.
• Yes, lunar cycles do appear to subtly influence human sleep, in a repeating sinusoidal pattern—but the mechanism remains a mystery.
• Biology is complex, and open questions remain about how deeply humans might be affected by subtle natural cycles.

Further Reading and References

• 52 citations for this episode are available in the transcript show notes.

Follow-up:

• Share your thoughts @ScienceVS (Instagram) or follow host Wendy Zuckerman on TikTok.
• Listen and subscribe for more myth-busting science!