The idea that a full moon can stir up emotions, provoke bizarre behavior, and even cause physical illness isn’t just a literary trope. It’s a strongly held belief, even today. In fact, one study says that nearly 81 percent of mental health professionals believe the full moon can make people ill.

“During the new moon, the moon isn’t visible in the sky. There’s no light, which means the energy available to us is low,” astrologer Kristen Fletcher, tells Bustle. “People often report feeling tired during a new moon and naturally crave turning inward.” They tend to become more self-reflective at this time.

The full moon can feel like a bit of a disruptive time, resulting in more erratic behaviour, tension, or tiredness. You may find yourself feeling anxious or emotionally upset. Research has shown that we actually sleep less on the full moon, so it’s important to ensure you care for your body.

Dr. Alex Dimitriu, who is double board-certified in psychiatry and sleep medicine, said the moon most likely exerts its effect by an increase in evening or nighttime light. This might suppress melatonin (a sleep hormone), which affects the onset and duration of sleep.

If you wake up at 3 a.m. or another time and can’t fall right back asleep, it may be for several reasons. These include lighter sleep cycles, stress, or underlying health conditions. Your 3 a.m. awakenings may occur infrequently and be nothing serious, but regular nights like this could be a sign of insomnia.

The full moon has been associated with strange or insane behavior, including suicide, sleepwalking and violence. The lunar theory, otherwise known as the lunar effect, is the idea that there’s some correlation between moon cycles and human behavior.