Many years ago during my medical residency training at UCLA, I spent time in the emergency room. You can imagine how interesting it could be to work a graveyard shift, and that seemed especially true if it happened to fall on a night with a full moon. Nurses warned me to be ready for anything on those nights. Even today, there are times when my receptionist will look at
me, raise her eyebrows, and suggest that there must be a full moon.

Could the phase of the moon alter our physical or mental state? Ancient Assyrian and Babylonian discuss this. Note that the word *lunatic* was derived from the Latin word *luna*, meaning moon.

The human body is made up of about 75% water. The moon (along with the sun) causes the tides. Could these gravitational tides affect our body? The effect of gravity diminishes with distance but never goes away; in theory everything is always tugging on everything else. Do note that the highest tides occur both on full and new moons - yet no one seems to connect
strange behaviors or events to new moons!

Over the years, researchers have searched for any statistical connection between the moon and human biology or behavior. Reliable studies comparing the lunar phases to births, deaths, heart attacks, suicides, violence, psychiatric hospital admissions, emergency room visits, epileptic seizures, surgical outcomes, menstruation, and sleep habits (to list just a few) have
simply found no significant correlation. Many studies that claimed to find connections turned out to have used flawed methods, or have not been able to be reproduced.

A frequently quoted study was performed by an international group of scientists, who examined the sleep patterns of children and differences in their daily activities. The findings revealed that during full and new moons, the children in the study slept five fewer minutes. The change in sleep represented about a 1% decrease, with no noticeable change in daily
activity.

One statistically significantly study performed by the Colorado State University Veterinary Medicine Center involved almost 12,000 participants: dogs and cats. During a full moon, emergency room visits increased by 28% for dogs and increased by 23% for cats. How this single study would relate to human behavior is unclear.

Certainly there are creatures that shape their lives around the tides. The behavior of coastal wading birds and the breeding of the California Grunion (fish) are good examples of that.

So, why does this myth persist so stubbornly? Perhaps when I was a resident in that UCLA emergency room, knowing that it was a full moon, I interpreted traumas and crises as more extreme or bizarre. Perhaps when strange things happen during a full moon, we tend to make that connection, but when strange things happen over the rest of the month, we don’t automatically connect them to astronomic events. Perhaps, before electricity, the light of the full moon kept people up at night, causing sleep deprivation and associated psychological issues.

Whatever the reason, I think that we can comfortably discard this very old myth!