The most ubiquitous of the stimulants is caffeine, found in coffee, tea, and soft drinks and in over the-counter analgesics and headache pills.

Coffee is the strongest of the beverages; one strong cup of real coffee may contain caffeine equivalent to the minimal stimulant dose. It is made from the roasted beans of the tropical coffee bush. Coffee was introduced into England in 1601 and popularised on medical grounds. Later `coffee shops’ spread as a forum for male social and political activities, provoking governmental licensing restrictions and suppression.

A cup of tea generally contains less, but can contain almost as much caffeine as instant coffee. It comes from the dried leaves of a shrub native to South East Asia and was introduced into Britain again as a medicine, in 1661, but soon became popular as a ”pick-me-up”. Despite opposition, by the late 1700s tea had ousted coffee as the national beverage and had become one of the State’s chief sources of revenue

Soft drinks also generally contain less caffeine than coffee but because of their lower body weight, children consuming a full Can could ingest the caffeine equivalent of four cups of coffee.

Caffeine itself is a white powder used as a mild stimulant in various preparations, though it is also used for some headaches and has diuretic properties. Fencamfamin ( Reactivan ) and pemoline ( Ronyl, Volital ) are mild stimulants, sometimes prescribed for debility and fatigue, with effects generally similar to caffeine

LEGAL STATUS

Caffeine is not subject to any legal prohibitions on its manufacture, sale, distribution or possession,

Fencarnfamin and pemoline are also not controlled under the Misuse of Drugs Act, but both are Prescription Only under the Medicines Act. Their sale is limited to a registered pharmacy in accordance with a prescription, although it is not illegal to possess them without a prescription, nor to give them away.

PREVALENCE & AVAILABILITY

Caffeinated beverages are sold without restriction everywhere and employers make them available to their workforce during rest breaks. Offering tea or coffee is a customary form of hospitality to visitors, and there can hardly be a restaurant or cafe in the country that does not provide one, the other, or both.

Seventy per cent of all UK Adults drink coffee and 86% drink tea. On average each coffee drinker consumes over three cups a day, whilst per capita tea consumption averages over four cups a day. From these and other sources, daily caffeine consumption in Britain averages over 440mg per person.

Each cup of brewed coffee provides an average 115mg (drip method) or 80mg (percolated) of caffeine. Instant coffee provides about 65mg, tea 60mg, and a can or bottle of soft drink from 30 to 50mg, all with wide variations depending on .the amount used, method of preparation, etc. These compare with the standard stimulant dose of 200mg.

Caffeine is an ingredient in a variety of proprietary analgesics, generally also available without restriction. In the UK over a million people take these pills every day, and some of the most well known brands contain caffeine. With up to 50mg in each tablet it would be easy for someone to add as much again to their caffeine consumption from beverages

SHORT TERM USE

Caffeine is a nervous system stimulant. In moderate doses (l50-250mg) the drug allays drowsiness, fatigue and postpones the onset of sleep. This helps prevent boredom and tiredness, which interferes with performance on manual and intellectual tasks. Larger doses impair performance, especially where delicate co-ordination of movement is required. There are increased feelings of alertness, or sometimes of anxiety. Physiological effects can include increased heart rate, raised blood pressure, increased excretion of urine (these diminish with repeated use), constriction of blood vessels in the brain (relieving some types of headache) and increased breathing. Coffee-even decaffeinated coffee-increases stomach acidity. ¬Effects of coffee are evident within an hour, lasting 3-4 hours. Afterwards there can be a ‘let down’ effect of increased fatigue.

EXCESSIVE USE

Consumption of 500-600mg of caffeine a day can cause feelings of anxiety and restlessness. If more than 1 gram of caffeine has been taken in one go (say 15 cups of instant coffee) the physiological effects may become pronounced. This may cause an increase in sensitivity and sensory disturbances (like ringing in the ear and light flashes), together with insomnia, muscle tremor, abnormally elevated heart rate and breathing. Gastrointestinal complaints such as nausea vomiting and diarrhoea may occur. Restlessness and excitement may progress to delirium. Death from over-dose is possible but very unlikely and very rare (it would normally take over 100 cups of coffee

LONG-TERM USE

People consuming the caffeine equivalent of seven or more cups of strong coffee a day may feel chronically anxious and irritable. They may experience muscle tremor and headaches. The stimulant effect may also cause chronic insomnia, but all these disturbances will clear up once caffeine intake is reduced.

Tolerance develops to many (but not all) of the physiological effects of caffeine, and there is a well-established withdrawal syndrome, noticeable after regular use of about 370mg a day (3 cups of strong coffee). On discontinuing, the habitual user feels less alert and relaxed, more drowsy and irritable, and may experience headaches which can be severe.  Regular drinkers often feel tired and irritable if they miss their usual morning coffee. Dependence, mainly Psychological, can develop to the extent that people find it hard to stop drinking coffee, even for medical reasons.

Evidence that heavy, long-term coffee drinking increases the risk of peptic ulceration, heart disease and certain cancers is inconclusive and adverse effects are likely to be infrequent and generally slight. However, individuals suffering from ulcers, high blood pressure or anxiety, may find that excessive caffeine/coffee consumption aggravates their condition.

Finally, some coffee contains a substance called kahweol which raises cholesterol levels. Some type of coffee have high levels (Arabica) and others contain none (Robusta). Brewing your coffee in paper filters results in lower levels of kehweol as the paper absorbs some of it.

“We have seen several well-marked cases of coffee excess. The sufferer is tremulous, and loses his self-command, he is subject to fits of agitation and depression, he loses colour and has a haggard appearance. The appetite falls off and symptoms of gastric catarrh may be manifested. The heart also suffers, it palpitates, or it intermits. As with other such agents, a renewed dose of the poison gives temporary relief, but at the cost of future misery.”
Sir T C Allbutt and H.D. Rolleston. A system of medicine.l909.