Can People Sleep Too Much? Effects of Extended Sleep Opportunity on Sleep Duration and Timing.

Many people are concerned about whether they are getting "enough" sleep, and if they can "sleep too much." These concerns can be approached scientifically using experiments probing long-term (i.e.

Longitudinal observations call into question the scientific consensus that humans are unaffected by lunar cycles.

Recent longitudinal observations show that human menstrual cycles, sleep-wake cycles and manic-depressive cycles can become synchronized with lunar cycles, but do so in uniquely complex and heterogeneous ways that are unlikely to have been detected by past studies. Past studies' negative results have given rise to a scientific consensus that human biology and behavior are unaffected by lunar cycles. The recent observations show that synchrony can be temporary, and can occur with more than one type of lunar cycle, more than one phase of a lunar cycle and more than one resonant frequency of a lunar cycle.

Women temporarily synchronize their menstrual cycles with the luminance and gravimetric cycles of the Moon.

Many species synchronize reproductive behavior with a particular phase of the lunar cycle to increase reproductive success. In humans, a lunar influence on reproductive behavior remains controversial, although the human menstrual cycle has a period close to that of the lunar cycle. Here, we analyzed long-term menstrual recordings of individual women with distinct methods for biological rhythm analysis.

Synchrony Between Bipolar Mood Cycles and Lunar Tidal Cycles Ended After Initiation of Light Treatment and Treatment of Hypothyroidism.

According to a recent report, mood cycles in a group of patients with rapid cycling bipolar disorder oscillated in synchrony with lunar gravimetric tides. Mood switches in a 67-year-old woman with rapid cycling bipolar II disorder on lithium maintenance treatment were assessed with a χ periodogram and a χ analysis of the mood switches in relation to the lunar tidal cycle. During a period when she was treated with nortriptyline and her thyroid-stimulating hormone levels were elevated, her mood switches had a significant (P<0.