What Is Caffeine?
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is the world’s most widely consumed psychoactive drug. Unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world. There are several known mechanisms of action to explain the effects of caffeine. The most prominent is that it reversibly blocks the action of adenosine on its receptors and consequently prevents the onset of drowsiness induced by adenosine. Caffeine also stimulates certain portions of the autonomic nervous system.
Caffeine is a bitter, white crystalline purine, a methylxanthine alkaloid, and is chemically related to.the adenine and guanine of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). It is found in the seeds, nuts, or leaves of a number of plants native to Africa, East Asia and South America, and helps to protect them against herbivory and from competition by preventing the germination of nearby seeds.The most well-known source of caffeine is the coffee bean, the seed of the Coffea plant. People may drink beverages containing caffeine to relieve or prevent drowsiness and to improve cognitive performance. To make these drinks, caffeine is extracted by steeping the plant product in water, a process called infusion. Caffeine-containing drinks, such as coffee, tea, and cola, are very popular; as of 2014, 85% of American adults consumed some form of caffeine daily, consuming 164 mg on average.
Caffeine can have both positive and negative health effects. It can treat and prevent the premature infant breathing disorders bronchopulmonary dysplasia of prematurity and apnea of prematurity. Caffeine citrate is on the WHO Model List of Essential Medicines. It may confer a modest protective effect against some diseases,including Parkinson’s disease. Some people experience sleep disruption or anxiety if they consume caffeine, but others show little disturbance. Evidence of a risk during pregnancy is equivocal; some authorities recommend that pregnant women limit caffeine to the equivalent of two cups of coffee per day or less Caffeine can produce a mild form of drug dependence – associated with withdrawal symptoms such as sleepiness, headache, and irritability – when an individual stops using caffeine after repeated daily intake. Tolerance to the autonomic effects of increased blood pressure and heart rate, and increased urine output, develops with chronic use (i.e., these symptoms become less pronounced or do not occur following consistent use
- Bronchopulmonary dysplasia in premature infants for both prevention and treatment.It may improve weight gain during therapyand reduce the incidence of cerebral palsy as well as reduce language and cognitive delay.On the other hand, subtle long-term side effects are possible.
- Apnea of prematurity as a primary treatment, but not prevention.
- Orthostatic hypotension treatment.
- Some people use caffeine-containing beverages such as coffee or tea to try to treat their asthma. Evidence to support this practice, however, is poor.It appears that caffeine in low doses improves airway function in people with asthma, increasing forced expiratory volume (FEV1) by 5% to 18%, with this effect lasting for up to four hours.
- The addition of caffeine (100–130 mg) to commonly prescribed pain relievers such as paracetamol or ibuprofen modestly improves the proportion of people who achieve pain relief.
Caffeine is a central nervous system stimulant that reduces fatigue and drowsiness.At normal doses, caffeine has variable effects on learning and memory, but it generally improves reaction time, wakefulness, concentration, and motor coordination.The amount of caffeine needed to produce these effects varies from person to person, depending on body size and degree of tolerance. The desired effects arise approximately one hour after consumption, and the desired effects of a moderate dose usually subside after about three or four hours.Caffeine can delay or prevent sleep and improves task performance during sleep deprivation. Shift workers who use caffeine make fewer mistakes that could result from drowsiness.A systematic review and meta-analysis from 2014 found that concurrent caffeine and l-theanine use has synergistic psychoactive effects that promote alertness, attention, and task switching;these effects are most pronounced during the first hour post-dose