Questions patients ask

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Q: Will drinking coffee make me more alert?

A: Yes. Many rigorous studies have demonstrated the beneficial effects of caffeine in coffee on both concentration and alertness1-3.

Q: Will drinking coffee affect my memory?

A: Some studies have shown that caffeine intake can improve memory. Low doses of caffeine are linked to a boost in memory performance, while higher doses are found to decrease it, possibly due to over-stimulation. Caffeine is particularly effective at improving memory under conditions that might otherwise produce low arousal states, i.e. during tedious, repetitive or dull tasks, such as long distance driving4.

Q: I have read somewhere that caffeine improves mood. Is this true?

A: Yes. Studies have shown that moderate intakes of caffeine (200mg) may help improve mood. A typical cup of coffee contains 75-100mg caffeine.  Research also suggests that drinking coffee may make us feel more sociable, which helps alleviate depressive symptoms5. Studies have shown that people who consume coffee/caffeine regularly may be less likely to develop depression6-9.

Q: Are the beneficial effects of coffee due to caffeine?

A: Yes, the benefits of coffee on mental performance are primarily due to the stimulatory effect of caffeine. There is convincing evidence that moderate caffeine intake helps to improve alertness and concentration1.

Q: Will drinking coffee before going to bed make it difficult to fall asleep, or affect the quality of my sleep?

A: This can vary from person to person. The effects of coffee on sleep patterns depend not only on the amount of caffeine ingested at bedtime, but also on the amount of caffeine consumed throughout the day, or during the hours leading up to sleep10,11. There are many external factors that may affect how long it takes someone to get to sleep, such as noise, temperature, and discomfort. That said, some research suggests that abstaining from caffeine can help to improve sleep12. Anyone who is particularly sensitive to the stimulant effects of caffeine can simply switch to decaffeinated coffee during the afternoon and evening.

Q: Should I avoid coffee during the afternoon to help me sleep better?

A: Some people find that they sleep better if they avoid caffeinated beverages before going to bed, whilst others are not affected by caffeine even immediately before bedtime10,11. Anyone who is particularly sensitive to the stimulant effects of caffeine can simply switch to decaffeinated coffee during the afternoon and evening.

Q: Can coffee help keep me alert if I work night shifts?

A: Yes, drinking caffeinated coffee can help some of us stay alert during shift work, especially if work hours are scheduled during the typical sleep period. Research investigating the effects of caffeine on shift work and jet lag has shown that drinking coffee can also reduce the number of errors and improve performance in shift workers13.

Q: Can coffee help me stay alert when I’m driving at night?

A: Research suggests that drinking a strong coffee (125ml containing approximately 200mg caffeine) and/or taking a short nap (15-30 minutes) are very effective at reducing driving impairment, and this improvement is greater when coffee and a short nap are combined14,15.

Q: Can coffee help with alertness in those who drive for long periods of time?

A: It is well established that drinking 1-2 cups of coffee improves alertness and concentration, which helps to aid safer driving. Furthermore, research has shown that drinking caffeinated beverages, such as coffee, is associated with a reduced risk of crashing for long-distance commercial vehicle drivers16.

Q; Can coffee help to alleviate the symptoms of jet lag?

A: Yes, drinking coffee is associated with increased alertness and may help to manage the feelings of sleepiness associated with jet lag. However, for those taking short stopovers of 1-2 days in a different time zone, adapting to the local clock may not the best strategy. Sensible naps, combined with a moderate intake of caffeine during times of appropriate wakefulness and short-term use of sleeping aids, appear to be the most effective ways to maintain alertness and sleep in these situations17.

Q: Is coffee addictive?

A: Addiction is commonly defined as a physical and psychological dependence on a ‘mind altering’ substance. While coffee has some ‘drug-like’ properties, i.e. caffeine in coffee is a stimulant, studies using brain scans suggest that moderate coffee drinkers do not develop a physical dependence on caffeine. Caffeine does not fulfil the criteria to be described as a drug of dependence18. In addition, in 1994, the World Health Organization stated that: ‘there is no evidence whatsoever that caffeine use has even remotely comparable physical and social consequences which are associated with serious drugs of abuse’19.

Q: If I stop drinking coffee, will I experience withdrawal symptoms?

A: ‘Caffeine withdrawal’ has been classified by the American Psychiatric Association as ‘a syndrome resulting from abrupt cessation or reduction in caffeine, following prolonged daily use’19. A small number of people may experience some mild withdrawal symptoms, such as headache, reduced alertness and drowsiness, if they suddenly remove coffee or caffeine from their diet. However, individuals who gradually reduce their caffeine intake over a couple of days tend not to experience these symptoms21.


  1. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) (2011) Scientific Opinion on the substantiation of health claims related to caffeine and increased fat oxidation leading to a reduction in body fat mass (ID 735, 1484), increased energy expenditure leading to a reduction in body weight (ID 1487), increased alertness (ID 736, 1101, 1187, 1485, 1491, 2063, 2103) and increased attention (ID 736, 1485, 1491, 2375) pursuant to Article 13(1) of Regulation (EC) No 1924/20061. EFSA Journal, 9(4):2054.
  2. Einother S.J.L. & Giesbrecht T. (2012) Caffeine as an attention enhancer: reviewing existing assumptions. Psychopharmacology, 225(2):251-274.
  3. Nehlig A. (2016) Effects of coffee/caffeine on brain health and disease: What should I tell my patients? Pract Neurol, 16(2):89-95.
  4. Nehlig A. (2010) Is Caffeine a Cognitive Enhancer? J Alzheimers Dis, 20(S1):85-94.
  5. Tse W.S. et al. (2009) Caffeinated coffee enhances co-operative behavior in the Mixed Motive Game in healthy volunteers. Nutr Neurosci, 12:21-7.
  6. Lucas M. et al. (2011) Coffee, caffeine, and risk of depression among women. Arch Intern Med, 171:1571-8.
  7. Ruusunen A. et al. (2010) Coffee, tea and caffeine intake and the risk of severe depression in middle-aged Finnish men: the Kuopio Ischaemic Heart Disease Risk Factor Study. Public Health Nutr, 13:1215-20.
  8. Pham N.M. et al. (2013) Green tea and coffee consumption is inversely associated with depressive symptoms in a Japanese working population. Pub Health Nutr, 4:1-9.
  9. Grosso G. et al. (2016) Coffee, tea, caffeine and risk of depression: a systematic review and dose-response meta-analysis of observational studies. Mol Nutr Food Res, 60(1):223-34.
  10. Drake C. et al. (2013) Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed. J Clin Sleep Med, 9(11):1195-1200.
  11. Clark I. and Landolt H.P. (2016) Coffee, Caffeine, and Sleep. Sleep Med Rev, doi:10.1016/j.smrv.2016.01.006, published online ahead of print.
  12. Sin C.W.M. et al. (2008) Systematic review on the effectiveness of caffeine abstinence on the quality of sleep. J Clin Nursing, 18:13-21.
  13. Ker K. et al. (2010) Caffeine for the prevention of injuries and errors in shift workers. Cochrane Database Syst Rev, (5):CD008508.
  14. Philip P. et al. (2006) The effects of coffee and napping on nighttime highway driving: a randomized trial. Ann Intern Med, 144:785-91.
  15. Horne J. et al. (1999) Vehicle accidents related to sleep: a review. Occup Environ Med, 56:289-94.
  16. Sharwood L.N. et al. (2013) Use of caffeinated substances and risk of crashes in long distance drivers of commercial vehicles: case control study. BMJ, 346:1140.
  17. Arendt J. (2009) Managing jet lag: Some of the problems and possible new solutions. Sleep Med Rev, 13:249-56.
  18. Nehlig A. et al. (2010) SPECT assessment of brain activation induced by caffeine: no effect on areas involved in dependence. Dialogues Clin Neurosci, 12:255-63.
  19. World Health Organisation (1994) The ICD-10 classification of mental and behavioral disorders. World Health Organisation, Geneva.
  20. American Psychiatric Association (2013) Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM V) ISBN 978-0-89042-554-1DSMV.
  21. Nehlig A. (2004). Are we dependent on coffee and caffeine: an update. In Nehlig A, ed. Coffee, Tea, Chocolate and the Brain. Boca Raton, FL: CRC Press, 133-146.

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