Caffeine and Work

Caffeine and Work

Where is it found?

Caffeine naturally occurs in plants such as tea, coffee and cocoa and is also added to energy drinks, and some other substances such as painkillers. It can temporarily ward off drowsiness and restore alertness, and is so ubiquitous we rarely think of it as a drug.

How Much Caffeine would be in…..

  • ? Can of cola: 40 mg
  • ? Small (250 ml) can of energy drink, or shot of energy drink: around 80 mg
  • ? Large (500 ml) energy drink: around 160 mg
  • ? 50 g bar of milk chocolate: up to 25 mg
  • ? 50 g bar of plain chocolate: up to 50 mg
  • ? A mug of instant coffee: 100 mg
  • ? Or filter coffee: 140 mg
  • ? Big mug of tea: 75 mg (depending on how they are made)
coffee beans in a c
caffeine and work

Science Facts about Caffeine

Caffeine is a legal stimulant drug. temporarily warding off drowsiness and restoring alertness. Beverages containing caffeine, such as coffee, tea, soft drinks and energy drinks enjoy great popularity. It has been found that in North America, 90% of adults consume caffeine daily.

Part of the reason caffeine is recognised as safe is that toxic doses (over 1 gram for an average adult) are much higher than typically used doses (less than 500 milligrams). Ordinary consumption can have low health risks, even when carried on for years although there may be a modest protective effect against some diseases. Some people experience sleep disruption if they consume caffeine, especially during the evening hours, but others show little disturbance. If you look at the video below you can see the effect of caffeine on sleep is highly variable because the amount of caffeine needed to produce effects varies from person to person, depending on body size and degree of tolerance. Effects begin less than an hour after consumption, and a moderate dose usually wears off in about five hours [1].

With heavy use of caffeine, workers tend to get used to the faster heart rate and twitching of muscles for the improved alertness and energy effects of caffeine. The degree to which caffeine can produce dependency and addiction is debatable.

In shift workers research has shown that caffeine use leads to fewer mistakes caused by tiredness

Effect on the Body

Watch this short video from Ted Ed on how caffeine actually works on the body:

How much is healthy?

In the UK, there are no clear recommendations for daily caffeine limits but in other countries the recommendation is 100 mg/day for adolescents.

Energy drinks

Energy drinks have high levels of caffeine and sugar, plus other ingredients. Many claim that these drinks are healthy. The EU requires drinks with more than 150mg of caffeine a litre must have a “high caffeine content” label and the British Soft Drinks Association recommends labelling energy drinks as ‘not suitable for children or pregnant women.’ However, these drinks are widely available and research suggest they are widely consumed.

Sleep impacts

Sleep disruption can affect concentration and achievement in the workplace the following day.

Caffeine withdrawal

Caffeine withdrawal symptoms are relatively common in adults. About half of regular caffeine users get a headache if they abstain, and other symptoms can include fatigue, difficulty concentrating, irritability and anxiety.  A recent programme on TV featured an experiment, A (not very) scientific experiment, showed two people stopped drinking their usual coffee but the headaches cleared after drinking two americanos (strong coffee) and two high caffeine drinks.

Caffeine and alcohol

A third of UK young people (aged 10-18) who drank energy drinks said they had mixed them with alcohol, implying a much higher proportion among older teenagers. This is concerning, as combining energy drinks and alcohol can lead to getting more drunk and engaging in risky behaviour. Caffeine makes people feel more alert when drunk and to take more risks.

Stopping Caffeine

The potential for caffeine withdrawal to cause clinically significant distress or impairment in functioning means that caffeine withdrawal is an official diagnosis in ICD-10 (World Health Organisation) and as a proposed diagnosis in DSM-IV (American Psychiatric Association).

Signs and symptoms. Here are the most common withdrawal symptoms:

      • Headaches
      • Fatigue — (e.g., fatigue, tiredness, lethargy, sluggishness)
      • Sleepiness/drowsiness — (e.g., sleepy, drowsy, yawning)
      • Difficulty concentrating — (e.g., muzzy)
      • Work difficulty — (e.g., decreased motivation for tasks/work)
      • Irritability — (e.g., irritable, cross, miserable, a decrease in well-being/contentedness)
      • Depression — (e.g., depressed mood)
      • Anxiety — (e.g., anxious, nervous)
      • Flu-like symptoms — (e.g., nausea/vomiting, muscle aches/stiffness, hot and cold spells, heavy feelings in arms or legs)
      • Impairment in awareness and reaction time

About 15% of the general population report having stopped caffeine use completely, citing concern about health and unpleasant side effects

Time course of caffeine withdrawal. 

The caffeine withdrawal syndrome follows an orderly time course. Onset usually occurs 12 to 24 hours after stopping caffeine intake, although 36 hours has been observed. The most common time frame is 20 to 48 hours after abstinence. Withdrawal takes between 2 days to a week, although it can be longer.

Supply of Caffeine

Nowadays many employers provide coffee bars for their workers as an employee benefit and as a perk.  However, with all this information and employees declaring they cannot start the day without their caffeine ‘fix’, I wonder who gets the most benefit?

Recently a friend of mine was charge extra for having a decaffeinated coffee and could not understand why it cost more to have coffee with something taken out!  Did not make sense to her and with caffeine in its extracted state selling for $150 for 125 grams this seems rather incongruous to me too.


1.  Wikipedia on Caffeine

Further Reading:

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