Caffeine and Insomnia! What does the evidence say?
Are you suffering with insomnia and can’t get up without a cup of coffee in the mornings?
Lets have a look at the research.
In a systematic review of 58 studies including observational studies, randomised placebo controlled trials, epidemiological and open label clinical trials the authors found that caffeine plays a role in sleep quality (Clark & Ladolt 2016, pp.4-24). Big studies say coffee affects sleep!
Have you ever wondered why one person can drink a coffee and have a nap and another person can be kept awake for days?
Epigenetic differences in the CYP1A4 gene, other single nucleotide polymorphisms and adenosine neurotransmission may predict individual variances in the ability to metabolise caffeine and sensitivity to caffeine (Clark & Ladolt 2016, pp.4-24).
Dose and timing are also key when considering the effect of caffeine on sleep quality. The authors concluded that caffeine reduces the number of hours of sleep, increases time to fall asleep and impaired overall quality of the sleep (Clark & Ladolt 2016, pp.4-24).
That’s right folks ~ if you have insomnia then the coffee has to go!
Day time sleep and sleepiness were also observed to be affected by caffeine intake.
Caffeine is a xanthine alkaloid found in coffee, tea, chocolate and some other beverages that is known to stimulate arousal and wakefulness (Clark & Ladolt 2016, pp.4-24).
The same study refers to a survey of 183 female coffee drinkers revealing no associated impact on sleep in those who consumed >5 cups/d compared to increased sleep disturbance in those who consumed 1-2 cups/d. Overall survey results seemed to vary considerably with self-reported sleep quality based on number of cups of coffee per day and number of hours consumed before bed time (Clark & Ladolt 2016, pp.4-24).
The authors also note and consider differences in habitual coffee consumption on sensitisation and effect on sleep and observe that not all of the studies included for review account for this as a confounding factor (Clark & Ladolt 2016, pp.4-24).
We metabolise caffeine according to genetic polymorphisms!
The bottom line ~
Individual sensitivity to caffeine, genetic polymorphisms affecting our ability to metabolise caffeine, sleep hygiene practices including lifestyle recommendations such as avoiding screens and light in the hours leading up to bed time, regular sleep and wake times, daily exercise in the mornings not at night, avoidance of stimulants such as alcohol, caffeine and nicotine in the latter part of the day and good stress management and coping strategies go a long way to getting a good night’s rest (Clark & Ladolt 2016, pp.4-24).
Disclaimer: This information is not a substitute for personal health advice and is not intended to be personal health advice, see your health practitioner for personal health advice if anything you have read here raises any questions or concerns about your health.
Reference: Clark, I & Landolt, HP 2016, ‘Coffee, caffeine, and sleep: A systematic review of epidemiological studies and randomized controlled trials’, Sleep Medicine Reviews, pp.1-39.
