Coffee and Sleep

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Expert comment from our roundtable expert and moderator Dr Renata Riha, Consultant in Sleep and Respiratory Medicine at the Royal Infirmary, Edinburgh and Honorary Reader at the University of Edinburgh.

Coffee is a complex compound and arguably one of the most researched elements of the diet. It contains over 1,000 components, one of the most notable of which is caffeine. There is a strong psychological element to coffee consumption and it is often a deeply-ingrained part of many people’s daily rituals, particularly at the start of the day. As part of ISIC’s roundtable on coffee and sleep, we discussed the relationships between caffeine, coffee and sleep, looking at the latest scientific research.

In response to the pressures of modern life, some people are inadvertently disturbing their own sleep and failing to realise that they are not allowing themselves enough time in bed. With often-repeated and conflicting ‘statements’ about how many hours a night people need (ranging from Albert Einstein’s reported 10 hours per night to former UK Prime Minister Margaret Thatcher’s infamously brief four hours), it’s not surprising that people become confused over what’s right for them. ISIC’s roundtable report outlined the science surrounding coffee, caffeine and sleep whilst also suggesting ways in which healthcare professionals can help people who are particularly sensitive to the stimulating effects of caffeine manage their sleep regime.

Although it is difficult to quantify the exact amount of sleep required as it varies by individual, it is clear that adequate sleep contributes to normal cognitive function, including alertness and concentration. Sleep deprivation has been associated with an increased risk of glucose impairment and development of type 2 diabetes, and evidence is growing of a potential impact on lifespan1,2,3.

There is a large variability between individuals, however a number of factors have been identified that may impact the amount of sleep an individual takes. During the roundtable, we discussed the factors involved. These factors include:

  • Poor understanding about how much sleep is needed and why
  • Bedtime habits
  • Smoking, alcohol or caffeine consumption
  • Poor sleep hygiene
  • Work demands: e.g. shift work
  • Anxiety and stress
  • Poor bedroom environments
  • Pets and partners in the bedroom causing disturbances

Caffeine may have an impact on sleep for a number of reasons. For example, older adults tend to be more sensitive to the effects of high doses of caffeine on sleep. Some people may not realise that are they age, their metabolism changes and hence so may their caffeine tolerance.

The most common sources of caffeine in the diet are coffee, tea and caffeine-containing soft drinks such as colas and energy drinks. Whilst it is clear that some people are particularly sensitive to the stimulating effect of caffeine and should be advised to avoid caffeinated beverages later in the day to limit any impact on sleep, there are many beneficial effects associated with the stimulating effect of caffeine, including helping those suffering from jet lag, or those who work shift patterns or undertake monotonous tasks, such as long distance driving. There is significant individual variability in the cause of sleep problems and the impact of caffeine in the body, such that generic advice is difficult to provide. Consequently, those who have such problems and concerns should seek specific advice from a healthcare professional.

References

  1. Killgore W.D. (2010) Effects of sleep deprivation on cognition. Prog Brain Res, 185:105-29.
  2. Killick R. et al. (2012) Implications of sleep restriction and recovery on metabolic outcomes. J Clin Endocrinol Metab, 97(11):3876-90
  3. Knutson K.L. et al. (2007) The metabolic consequences of sleep deprivation. Sleep Med Rev, 11(3):159-62.

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