By changing the length of time we are exposed to varying intensities of light during a day, it is possible to affect the timing of melatonin production and disrupt our sleep patterns. This can be experienced with jet travel. As we traverse several time zones, our production of melatonin gets out of sync with the new time causing jet lag. Also, if one's job requires them to work different shifts, it can take days to get used to the new time resulting in feeling tired most of the time. Understanding circadian rhythms can be meaningful.
Vitality is lowest at midnight.
For example, death after surgery occurs three times as frequently at midnight than noon. Benefits of taking medications and supplements can be maximized taking these cycles into account. Biological clocks are known to become disorganized in diseased states. This lack of synchronization may not be a mere symptom but part of the disease itself. Light sets the timing mechanism of the brain's internal clock each morning as it enters the lens of the eye and stimulates the retina.