Afternoon is the time between noon and sunset or evening. [1] It is the time when the sun is descending from its peak in the sky to somewhat before its terminus at the horizon in the west. In human life, it occupies roughly the latter half of the standard work and school day. In literal terms, it refers to a time specifically after noon.
Afternoon is often defined as the period between noon and sunset. [2] If this definition is adopted, the specific range of time varies in one direction: noon is defined as the time when the sun reaching its highest point in the sky, [3] but the boundary between afternoon and evening has no standard definition. However, before a period of transition from the 12th to 14th centuries, noon instead referred to 3:00 pm. Possible explanations include shifting times for prayers and midday meals, along which one concept of noon was defined—and so afternoon would have referred to a narrower timeframe. [4]
The word afternoon, which derives from after and noon, has been attested from about the year 1300; Middle English contained both afternoon and the synonym aftermete. The standard phrasing was at afternoon in the 15th and 16th centuries, but has shifted to in the afternoon since then. [5] In American English dialects, the word evening is sometimes used to encompass all times between noon and midnight. [6] The Irish language contains four different words to mark time intervals from late afternoon to nightfall; this period is considered mystical. [7] Metaphorically, the word afternoon refers to a relatively late period in the expanse of time or in one's life. [2]
The equivalent of Earth's afternoon on another planet would refer to the time the principal star of that planetary system would be in descent from its prime meridian, as seen from the planet's surface.
Afternoon is a time when the sun is descending from its daytime peak. During the afternoon, the sun moves from roughly the center of the sky to deep in the west. In late afternoon, sunlight is particularly bright and glaring, because the sun is at a low angle in the sky. [8] The standard working time in most industrialized countries goes from the morning to the late afternoon or early evening — archetypally, 9:00 am to 5:00 pm — so the latter part of this time takes place in the afternoon. [9] Schools usually let their students out around 3:00 pm during the mid afternoon. [10] In Denmark, afternoon is considered between 1:00 and 5:00 pm. [11]
In diurnal animals, it is typical for blood levels of the hormone cortisol—which is used to increase blood sugar, aid metabolism and is also produced in response to stress—to be most stable in the afternoon after decreasing throughout the morning. However, cortisol levels are also the most reactive to environmental changes unrelated to sleep and daylight during the afternoon. As a result, this time of day is considered optimal for researchers studying stress and hormone levels. [12] Plants generally have their highest photosynthetic levels of the day at noon and in the early afternoon, owing to the sun's high angle in the sky. The large proliferation of maize crops across Earth has caused tiny, harmless fluctuations in the normal pattern of atmospheric carbon dioxide levels, since these crops photosynthesize large amounts of carbon dioxide during these times and this process sharply drops down during the late afternoon and evening. [13]
In humans, body temperature is typically highest during the mid to late afternoon. [14] However, human athletes being tested for physical vigor on exercise machines showed no statistically significant difference after lunch. [14] Owners of factory farms are advised to use buildings with an east–west (as opposed to north–south) orientation to house their livestock, because an east–west orientation generally means thicker walls on the east and west to accommodate the sun's acute angle and intense glare during late afternoon. When these animals are too hot, they are more likely to become belligerent and unproductive. [8]
The afternoon, especially the early afternoon, is associated with a dip in a variety of areas of human cognitive and productive functioning. Notably, motor vehicle accidents occur more frequently in the early afternoon, when drivers presumably have recently finished lunch. [15] A study of motor accidents in Sweden between 1987 and 1991 found that the time around 5:00 pm had by far the most accidents: around 1,600 at 5:00 pm, compared to around 1,000 each at 4:00 pm and 6:00 pm. This trend may have been influenced by the afternoon rush hour, but the morning rush hour showed a much smaller increase. [16] In Finland, accidents in the agriculture industry are most common in the afternoon, specifically Monday afternoons in September. [17]
One psychology professor studying circadian rhythms found that his students performed somewhat worse on exams in the afternoon than in the morning, but even worse in the evening. Neither of these differences, however, was statistically significant. [14] Four studies carried out in 1997 found that subjects who were given tests on differentiating traffic signs had longer reaction times when tested at 3:00 pm and 6:00 pm than at 9:00 am and 12:00 pm. These trends are held across all four studies and for both complex and abstract questions. [18] However, one UK-based researcher failed to find any difference in exam performance on over 300,000 A-level exam papers sat in either the morning or afternoon. [19]
Human productivity routinely decreases in the afternoon. Power plants have shown significant reductions in productivity in the afternoon compared to the morning, the largest differences occurring on Saturdays and the smallest on Mondays. [20] One 1950s study covering two female factory workers for six months found that their productivity was 13 percent lower in the afternoon, the least productive time being their last hour at work. It was summarized that the differences came from personal breaks and unproductive activities at the workplace. [21] Another, larger study found that afternoon declines in productivity were greater during longer work shifts. [22]
Not all humans share identical circadian rhythms. One study across Italy and Spain had students fill out a questionnaire, then ranked them on a "morningness–eveningness" scale. The results were a fairly standard bell curve. Levels of alertness over the course of the day had a significant correlation with scores on the questionnaire. All categories of participants—evening types, morning types, and intermediate types—had high levels of alertness from roughly 2:00 pm to 8:00 pm, but outside this window their alertness levels corresponded to their scores. [23]
A day is the time period of a full rotation of the Earth with respect to the Sun. On average, this is 24 hours. As a day passes at a given location it experiences morning, noon, afternoon, evening, and night. This daily cycle drives circadian rhythms in many organisms, which are vital to many life processes.
Daylight saving time (DST), also referred to as daylight saving(s), daylight savings time, daylight time (United States and Canada), or summer time (United Kingdom, European Union, and others), is the practice of advancing clocks to make better use of the longer daylight available during summer, so that darkness falls at a later clock time. The typical implementation of DST is to set clocks forward by one hour in spring or late winter, and to set clocks back by one hour to standard time in the autumn (or fall in North American English, hence the mnemonic: "spring forward and fall back").
Brunch is a meal, sometimes accompanied by alcoholic drinks, taken sometime in the late morning or early afternoon – the universally accepted time is 10am-1pm. The meal originated in the British hunt breakfast. The word brunch is a portmanteau of breakfast and lunch. The word originated in England in the late 19th century, and became popular in the United States in the 1930s.
A circadian rhythm, or circadian cycle, is a natural oscillation that repeats roughly every 24 hours. Circadian rhythms can refer to any process that originates within an organism and responds to the environment. Circadian rhythms are regulated by a circadian clock whose primary function is to rhythmically co-ordinate biological processes so they occur at the correct time to maximise the fitness of an individual. Circadian rhythms have been widely observed in animals, plants, fungi and cyanobacteria and there is evidence that they evolved independently in each of these kingdoms of life.
Noon is 12 o'clock in the daytime. It is written as 12 noon, 12:00 m., 12 p.m., 12 pm, or 12:00 or 1200 . Solar noon is the time when the Sun appears to contact the local celestial meridian. This is when the Sun reaches its apparent highest point in the sky, at 12 noon apparent solar time and can be observed using a sundial. The local or clock time of solar noon depends on the date, longitude, and time zone, with Daylight Saving Time tending to place solar noon closer to 1:00pm.
Advanced Sleep Phase Disorder (ASPD), also known as the advanced sleep-phase type (ASPT) of circadian rhythm sleep disorder, is a condition that is characterized by a recurrent pattern of early evening sleepiness and very early morning awakening. This sleep phase advancement can interfere with daily social and work schedules, and results in shortened sleep duration and excessive daytime sleepiness. The timing of sleep and melatonin levels are regulated by the body's central circadian clock, which is located in the suprachiasmatic nucleus in the hypothalamus.
A siesta is a short nap taken in the early afternoon, often after the midday meal. Such a period of sleep is a common tradition in some countries, particularly those in warm-weather zones. The "siesta" can refer to the nap itself, or more generally to a period of the day, generally between 2–5 p.m. This period is used for sleep, as well as leisure, mid-day meals, or other activities.
Polyphasic sleep is the practice of sleeping during multiple periods over the course of 24 hours, in contrast to monophasic sleep, which is one period of sleep within 24 hours. Biphasicsleep refers to two periods, while polyphasic usually means more than two. Segmented sleep and divided sleep may refer to polyphasic or biphasic sleep, but may also refer to interrupted sleep, where the sleep has one or several shorter periods of wakefulness, as was the norm for night sleep in pre-industrial societies.
In geography and geodesy, a meridian is the locus connecting points of equal longitude, which is the angle east or west of a given prime meridian. In other words, it is a line of longitude. The position of a point along the meridian is given by that longitude and its latitude, measured in angular degrees north or south of the Equator. On a Mercator projection or on a Gall-Peters projection, each meridian is perpendicular to all circles of latitude. A meridian is half of a great circle on Earth's surface. The length of a meridian on a modern ellipsoid model of Earth has been estimated as 20,003.93 km (12,429.87 mi).
Shift work is an employment practice designed to keep a service or production line operational at all times. The practice typically sees the day divided into shifts, set periods of time during which different groups of workers perform their duties. The term "shift work" includes both long-term night shifts and work schedules in which employees change or rotate shifts.
A phase response curve (PRC) illustrates the transient change in the cycle period of an oscillation induced by a perturbation as a function of the phase at which it is received. PRCs are used in various fields; examples of biological oscillations are the heartbeat, circadian rhythms, and the regular, repetitive firing observed in some neurons in the absence of noise.
A zeitgeber is any external or environmental cue that entrains or synchronizes an organism's biological rhythms, usually naturally occurring and serving to entrain to the Earth's 24-hour light/dark and 12-month cycles.
A night owl, evening person or simply owl, is a person who tends or prefers to be active late at night and into the early morning, and to sleep and wake up later than is considered normal; night owls often work or engage in recreational activities late into the night, and sleep until relatively late in the day.
Shift work sleep disorder (SWSD) is a circadian rhythm sleep disorder characterized by insomnia, excessive sleepiness, or both affecting people whose work hours overlap with the typical sleep period. Insomnia can be the difficulty to fall asleep or to wake up before the individual has slept enough. About 20% of the working population participates in shift work. SWSD commonly goes undiagnosed, so it's estimated that 10–40% of shift workers have SWSD. The excessive sleepiness appears when the individual has to be productive, awake and alert. Both symptoms are predominant in SWSD. There are numerous shift work schedules, and they may be permanent, intermittent, or rotating; consequently, the manifestations of SWSD are quite variable. Most people with different schedules than the ordinary one might have these symptoms but the difference is that SWSD is continual, long-term, and starts to interfere with the individual's life.
A chronotype is the behavioral manifestation of underlying circadian rhythm's myriad of physical processes. A person's chronotype is the propensity for the individual to sleep at a particular time during a 24-hour period. Eveningness and morningness are the two extremes with most individuals having some flexibility in the timing of their sleep period. However, across development there are changes in the propensity of the sleep period with pre-pubescent children preferring an advanced sleep period, adolescents preferring a delayed sleep period and many elderly preferring an advanced sleep period.
A lark, early bird, morning person, or an A-person, is a person who usually gets up early in the morning and goes to bed early in the evening. The term relates to the birds known as larks, which are known to sing before dawn. Human "larks" may sleep from around 10 p.m. to 6 a.m., and tend to feel most energetic just after they get up in the morning. They are thus well-suited for working the day shift.
The cortisol awakening response (CAR) is an increase between 38% and 75% in cortisol levels peaking 30–45 minutes after awakening in the morning in some people. This rise is superimposed upon the late-night rise in cortisol which occurs before awakening. While its purpose is uncertain, it may be linked to the hippocampus' preparation of the hypothalamic-pituitary-adrenal axis (HPA) in order to face anticipated stress.
Second wind, a colloquial name for the scientific term wake maintenance zone, is a sleep phenomenon in which a person, after a prolonged period of staying awake, temporarily ceases to feel drowsy, often making it difficult to fall asleep when exhausted. They are the result of circadian rhythms cycling into a phase of wakefulness. For example, many people experience the effects of a second wind in the early morning even after an entire night without sleep because it is the time when they would normally wake up.
The morningness–eveningness questionnaire (MEQ) is a self-assessment questionnaire developed by researchers James A. Horne and Olov Östberg in 1976. Its main purpose is to measure whether a person's circadian rhythm produces peak alertness in the morning, in the evening, or in between. The original study showed that the subjective time of peak alertness correlates with the time of peak body temperature; morning types have an earlier temperature peak than evening types, with intermediate types having temperature peaks between the morning and evening chronotype groups. The MEQ is widely used in psychological and medical research and has been professionally cited more than 4,000 times.
In Roman timekeeping, a day was divided into periods according to the available technology. Initially, the day was divided into two parts: the ante meridiem and the post meridiem. With the advent of the sundial circa 263 BC, the period of the natural day from sunrise to sunset was divided into twelve hours.
Media related to Afternoon at Wikimedia Commons
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