A new study, published in the journal Current Biology, examines the effects of lunar cycles on human sleep cycles.  The researchers identified that a lunar cycle existed to human sleep patterns.  The study examined delta activity in the brain during non-rapid eye movement (NREM) sleep, which is an indicator of deep sleep.  They also looked at the secretion of melatonin and cortisol, which also play a role in sleep.  Around the time of the full moon, total sleep time decreased by 20 minutes, time to fall asleep increased by five minutes, and indicators of deep sleep decreased by 30 percent.

The study was performed under strictly controlled settings.  The participants were not aware of the purpose of the study, but were kept in a dark room to fall asleep.  The possibility of light from the full moon influencing the sleep patterns was ruled out by using these controlled settings.  More light decreases melatonin produced by the body.  Having insufficient light during the day or bright lights in the evening can disturb melatonin production.  Melatonin helps regulate sleep cycles.

Circadian rhythms regulate sleep, as well as other physical, behavioral, and mental changes that occur over a period of 24 hours.  A group of nerve cells in the brain, together known as the suprachiasmatic nucleus (SCN), control the rhythms.  The SCN is located just above the eyes and uses information about light levels to produce melatonin.  Other environmental and genetic factors influence rhythm.

Lunar influence on the body has long been a source of myths.  A number of studies have focused on evaluating possible connections between lunar phases and births, heart attacks, violence, hospital admissions, surgery outcomes, seizures, and a variety of other results, finding little or no significant relationship.  However, this study shows that there exists some grain of truth behind all of the myths that persist.

Sleep is an important part of mental and physical well-being.  Continuously deficient sleep has been linked to higher risk of kidney disease, heart disease, high blood pressure, stroke, diabetes, and obesity. Adequate sleep also helps ensure brain functioning and emotional well-being, enhancing daytime performance.

Circadian rhythms can also be disturbed by sleep disorders related to the rhythms.  Delayed sleep phase disorder involves going to sleep at least two hours later and waking up later in the morning.  Advanced sleep phase disorder is the opposite condition, where the individual goes to sleep and wakes up several hours earlier.  Jet lag disorder is a temporary condition caused by disruption due to traveling across time zones.  Finally, irregular sleep-wake rhythm refers to any undefined disturbance in the rhythm.