According to the Food and Drug Administration, caffeine is widely available and upto 80% of adults have caffeine everyday, upto 200mg, which is about 10 ounces of coffee (1).
Sometimes caffeine is used to help stay awake, alert, keep up with academic demands, etc.
While the many benefits of caffeine have been widely documented, problems and side effects caffeine are not as widely known.
One study looked at the impact of caffeine on stress (2).
Who was involved in the study? (2)
- 25 participants who used caffeine regularly or were light user of caffeine.
- Subjects received placebo or caffeine (3.5mg per kilogram of body weight, about 238mg for a person weighing 150 pounds)
What was measured? (2)
- Blood pressure, cortisol (stress hormone), norepinephrine and epinephrine (also involved in stress response and other functions).
- Measurements were taken at rest, during a stressful laboratory task, and afterwards at rest.
What were the results? (2)
- Compared to placebo, caffeine caused more than DOUBLE the levels of epinephrine and cortisol, both involved in stress response.
- Effects were similar in both habitual and light users.
- Habitual use of caffeine did not development of tolerance to the bodily response.
- Even at rest, caffeine increased blood pressure and plasma norepinephrine levels.
What do the results mean?
Caffeine may increase your stress level whether you are using caffeine sporadically or regularly.
What are some other effects of too much caffeine?
- Caffeine had as early as 7am lead to less efficient sleep and reduced total sleep at 9pm (3).
- Some people have more daytime sleepiness because of caffeine related sleep disruption (4).
- Caffeine can reduce bloodflow to the brain by up to 27% (5)
- Too much caffeine can cause (1):
- Worsening of anxiety
- Sleep disturbance
- Make your heart beat faster, palpitations, high blood pressure, abnormal heart rhythms
What are some caveats?
- This is a small study and there are many studies showing positive and negative effects of caffeine.
- Not everyone has the same benefits or side effects caffeine.
- The AMOUNT of caffeine that has beneficial and harmful effects can be different for different people.
- Some people can metabolize caffeine much faster or slower than others (6).
- For some people, it can take days to weeks to see benefits from reducing or eliminating caffeine.
- Stopping caffeine abruptly can lead to withdrawal headaches, irritability, and other symptoms.
Are you feeling stressed, irritable or anxious? How is your caffeine intake? Could you benefit from less?
Disclaimer: This article is intended to be informative only. It is advised that you check with your own physician/mental health provider before implementing any changes. With this article, the author is not rendering medical advice, nor diagnosing, prescribing, or treating any condition, or injury; and therefore claims no responsibility to any person or entity for any liability, loss, or injury caused directly or indirectly as a result of the use, application, or interpretation of the material presented.
- Land JD, Adcock RA, Williams RB, Kuhn CM. Caffeine effects on cardiovascular and neuroendocrine responses to acute psychosocial stress and their relationship to level of habitual caffeine consumption. Psychosom Med. 1990 May-Jun;52(3):320-36.
- H.P. Landolt, E. Werth, A.A. Borbely, D.J. Dijk. Caffeine intake (200 mg) in the morning affects human sleep and EEG power spectra at night. Brain Research, 675 (1–2) (1995), pp. 67–74.
- T. Roehrs, T. Roth. Caffeine: sleep and daytime sleepiness. Sleep Med Rev, 12 (2) (2008), pp. 153–162.
- Addicott M.A., Yang L.L., Peiffer A.M., Burnett L.R., Burdette J.H., Chen M.Y.. et al. The effect of daily caffeine use on cerebral blood flow: how much caffeine can we tolerate? Hum. Brain Mapp. 2009;30:3102–3114.
- Cornelis, M. C. et al. Genome-wide meta-analysis identifies six novel loci associated with habitual coffee consumption. Mol. Psychiatry 20, 647–656 (2015).