question: Why are humans biologically wired to wake long past sunrise and go to sleep long past sunset, rather than waking and going to sleep around sunrise and sunset?
comment: They are not. Modern electrical lighting and society has shifted it. Try going camping for a week or so with only one flash light. You will wake and sleep more or less with the sun very quickly.
passages: All of the mechanisms of light-effected entrainment are not yet fully known, however numerous studies have demonstrated the effectiveness of light entrainment to the day/night cycle. Studies have shown that the timing of exposure to light influences entrainment; as seen on the phase response curve for light for a given species. In diurnal (day-active) species, exposure to light soon after wakening advances the circadian rhythm, whereas exposure before sleeping delays the rhythm. An advance means that the individual will tend to wake up earlier on the following day(s). A delay, caused by light exposure before sleeping, means that the individual will tend to wake up later on the following day(s).
   Early research into circadian rhythms suggested that most people preferred a day closer to 25 hours when isolated from external stimuli like daylight and timekeeping. However, this research was faulty because it failed to shield the participants from artificial light. Although subjects were shielded from time cues (like clocks) and daylight, the researchers were not aware of the phase-delaying effects of indoor electric lights. The subjects were allowed to turn on light when they were awake and to turn it off when they wanted to sleep. Electric light in the evening delayed their circadian phase. A more stringent study conducted in 1999 by Harvard University estimated the natural human rhythm to be closer to 24 hours and 11 minutes: much closer to the solar day.
   Sunrise and sunset are defined by the Road Vehicles Lighting Regulations as local sunrise and sunset so the times are different in different parts of the UK; they are earlier in the east and later in the west, and vary more with the seasons in northerly locations than in southerly locations.
   These effects make the day about 14 minutes longer than the night at the equator and longer still towards the poles. The real equality of day and night only happens in places far enough from the equator to have a seasonal difference in day length of at least 7 minutes, actually occurring a few days towards the winter side of each equinox.
  
  The times of sunset and sunrise vary with the observer's location (longitude and latitude), so the dates when day and night are equal also depend upon the observer's location.
   Section::::Recent developments.
  
  More recently, light therapy and melatonin administration have been explored by Alfred J. Lewy (OHSU), Josephine Arendt (University of Surrey, UK) and other researchers as a means to reset animal and human circadian rhythms. Additionally, the presence of low-level light at night accelerates circadian re-entrainment of hamsters of all ages by 50%; this is thought to be related to simulation of moonlight.
  
  Humans can have a propensity to be morning people or evening people; these behavioral preferences are called chronotypes for which there are various assessment questionnaires and biological marker correlations.
   Daytime becomes longer as the summer solstice approaches, while nighttime gets longer as the winter solstice approaches. This can have a potential impact on the times and durations of dawn and dusk. This effect is more pronounced closer to the poles, where the Sun rises at the vernal equinox and sets at the autumn equinox, with a long period of twilight, lasting for a few weeks.
   Work areas must have at least a value of 200 equivalent melanopic lux present for 75% or more work stations between the hours of 9:00 A.M. and 1:00 P.M. for each day of the year when daylight is incorporated into calculations. If daylight is not taken into account all workstations require lighting at the value of 150 equivalent melanopic lux or greater.
   The hormones cortisol and melatonin are effected by the signals light sends through the body's nervous system. These hormones help regulate blood sugar to give the body the appropriate amount of energy that is required throughout the day. Cortisol is levels are high upon waking and gradual decrease over the course of the day, melatonin levels are high when the body is entering and exiting a sleeping status and are very low over the course of waking hours. The earth's natural light-dark cycle is the basis for the release of these hormones.
   Section::::In animals.:Other environmental influences.
  
  Diurnality has shown to be an evolutionary trait in many animal species, with diurnality mostly reappearing in many lineages. Other environmental factors like ambient temperature, food availability, and predation risk can all influence whether an animal will evolve to be diurnal, or if their effects are strong enough, then mask over their circadian rhythm, changing their activity patterns to becoming diurnal. All three factors often involve one another, and animals need to be able to find a balance between them if they are to survive and thrive.
   This was not the first time that the idea of adapting to daylight hours had been mooted, however. It was common practice in the ancient world, and Benjamin Franklin's light-hearted 1784 satire resulted in resurrecting the idea. Although Franklin's facetious suggestion was simply that people should get up earlier in summer, he is often erroneously attributed as the inventor of DST while Willett is often ignored. Modern DST was first proposed by New Zealand entomologist George Vernon Hudson, although many publications incorrectly credit Willett.
   In the middle latitudes (between the tropics and the polar circles, where most humans live), the length of daytime, as well as solar altitude and azimuth, vary from one day to the next, and from season to season. The difference between the lengths of a long summer day and of a short winter day increases as one moves farther away from the Equator.
  
  Section::::Building design simulation.
   Likewise, the same phenomenon exists in the Southern Hemisphere, but with the respective dates reversed, with the earliest sunsets occurring some time before June 21 in winter, and latest sunsets occurring some time after December 21 in summer, again depending on one's southern latitude. For a few weeks surrounding both solstices, both sunrise and sunset get slightly later each day. Even on the equator, sunrise and sunset shift several minutes back and forth through the year, along with solar noon. These effects are plotted by an analemma.
   There is a tendency to draw time zone boundaries far to the west of their meridians. A reason is that it can allow the more efficient use of sunlight. Many of these locations also use DST, adding yet another nautical time zone to the east. As a result, in summer, solar noon in the Spanish town of Muxía occurs at 14:37 clock time, indeed very close to "awake time noon" (15:00). This westernmost area of continental Spain never experiences sunset before 18:00 clock time, even in midwinter, despite its lying more than 40 degrees north of the equator. Near the summer solstice, Muxía has sunset times (after 22:00) similar to those of Stockholm, which is in the same time zone and 16 degrees farther north. Stockholm has much earlier sunrises, though.
   Morning larks tend to thrive in careers that start early in the morning. Industries that tend to be favorable to morning larks include farming, construction, and working for public utilities. Many employees in these industries start working at or before 7:00 a.m. Some professions are well-known for their early morning hours, including bakers, school teachers, dairy farmers, and surgeons.
   BULLET::::- Day length is also affected by the variable orbital speed of the Earth around the Sun. This combined effect is described as the equation of time. Thus even locations which lie on their time zone's reference meridian will not see sunrise and sunset at 6:00 and 18:00. At the March equinox they are 7–8 minutes later, and at the September equinox they are about 7–8 minutes earlier.
   Industrialized societies usually follow a clock-based schedule for daily activities that do not change throughout the course of the year. The time of day that individuals begin and end work or school, and the coordination of mass transit, for example, usually remain constant year-round. In contrast, an agrarian society's daily routines for work and personal conduct are more likely governed by the length of daylight hours and by solar time, which change seasonally because of the Earth's axial tilt. North and south of the tropics daylight lasts longer in summer and shorter in winter, with the effect becoming greater the further one moves away from the tropics.
   Modern humans often find themselves desynchronized from their internal circadian clock, due to the requirements of work (especially night shifts), long-distance travel, and the influence of universal indoor lighting. Even if they have sleep debt, or feel sleepy, people can have difficulty staying asleep at the peak of their circadian cycle. Conversely they can have difficulty waking up in the trough of the cycle. A healthy young adult entrained to the sun will (during most of the year) fall asleep a few hours after sunset, experience body temperature minimum at 6 a.m., and wake up a few hours after sunrise.
   Sunset is distinct from twilight, which is divided into three stages, the first being "civil" twilight, which begins once the Sun has disappeared below the horizon, and continues until it descends to 6 degrees below the horizon; the second phase is "nautical" twilight, between 6 and 12 degrees below the horizon; and the third is "astronomical" twilight, which is the period when the Sun is between 12 and 18 degrees below the horizon. "Dusk" is at the very end of astronomical twilight, and is the darkest moment of twilight just before night. Night occurs when the Sun reaches 18 degrees below the horizon and no longer illuminates the sky.
   Research suggests that sleep patterns vary significantly across cultures. The most striking differences are observed between societies that have plentiful sources of artificial light and ones that do not. The primary difference appears to be that pre-light cultures have more broken-up sleep patterns. For example, people without artificial light might go to sleep far sooner after the sun sets, but then wake up several times throughout the night, punctuating their sleep with periods of wakefulness, perhaps lasting several hours.
   Exposure to light, or lack thereof, plays a significant role in sleep cycles. All animals, including humans, have evolved circadian rhythms, which respond to the earth's 24-hour cycle. These rhythms include the sleep–wake cycle, hormone production, and core body temperature cycles. The timing of these patterns is set by the 24-hour light–dark cycle. In particular, short-wavelength "blue" light in the daylight spectrum has maximal effect on human circadian rhythms. Research has shown that when these patterns are disrupted, individuals are more susceptible to ailments such as breast cancer, obesity, sleep deprivation, mood disorders, and other health problems.
   Section::::Adaptive Relevance.:Matutinal Mating.
  
  For certain species, commencing mating during the early morning's twilight period may be adaptive because it could reduce the risk of predation, increase the chance of finding mates, and reduce competition for mates, all of which may increase reproductive success.
  
  Section::::Adaptive Relevance.:Matutinal Mating.:Anti-Predatory Adaptation.
   For most diurnal animals, the day naturally begins at dawn and ends at sunset. Humans, with their cultural norms and scientific knowledge, have employed several different conceptions of the day's boundaries. Common convention among the ancient Romans, ancient Chinese and in modern times is for the civil day to begin at midnight, i.e. 00:00, and last a full 24 hours until 24:00 (i.e. 00:00 of the next day). 
  
  In ancient Egypt, the day was reckoned from sunrise to sunrise. The Jewish day begins at either sunset or nightfall (when three second-magnitude stars appear).
   The WELL Building standard additionally provides direction for circadian emulation in multi-family residences. In order to more accurately replicate natural cycles lighting users must be able to set a wake and bed time. A equivalent melanopic lux of 250 must be maintained in the period of the day between the indicated wake time and two hours before the indicated bed time. An equivalent melanopic lux of 50 or less is required for the period of the day spanning from two hours before the indicated bed time through the wake time. In addition at the indicated wake time melanopic lux should increase from 0 to 250 over the course of at least 15 minutes.
   Section::::Work.:Aschoff–Wever Model.
  
  1) An increase in the duration of sunset advances the phase of an organism for nocturnal and diurnal animals.
  
  2) An increase in strength of the zeitgeber should increase as sunset duration increases.
  
  Section::::Work.:Influence on other researchers.
   Section::::In animals.:Light.
  
presuppositions: Humans are wired to wake after sunrise and sleep after sunset. Humans are biologically wire to wake past sunrise and sleep past sunset.
corrections: Civilization changed human sleeping patterns, we naturally wake at sunrise and sleep at sunset. Modern electrical lighting and societal customs have allowed humans to wake past sunrise and sleep past sunset.
raw_presuppositions: Humans are wired to wake after sunrise and sleep after sunset. Humans are biologically wire to wake past sunrise and sleep past sunset.
raw_corrections: Civilization changed human sleeping patterns, we naturally wake at sunrise and sleep at sunset. Modern electrical lighting and societal customs have allowed humans to wake past sunrise and sleep past sunset.