One of the most studied areas of lunar influence is sleep. A 2021 study found that people tend to go to bed later and sleep less in the nights leading up to a full moon, likely due to reduced levels of melatonin—the hormone that regulates sleep and wakefulness. The researchers observed that this effect was strongest in communities with limited access to artificial light, implying that the brightness of the full moon might subtly interfere with natural circadian rhythms. Even if the moon’s glow no longer dictates our nightly routines, our biology may still carry traces of an earlier, more light-sensitive past.
