Research Critique: the Effects of Caffeine Abstinences on Sleep

Category: Article Critique


The title “The Effects of Caffeine Abstinences on Sleep: A Pilot Study” reveals the reader that this article is going to discuss the influence of caffeine beverages on sleep. The title is clear and gives the opportunity for complete understanding of the topic. Moreover, the additional part of the title “A Pilot Study” explains that, firstly, this investigation does not have much background and, secondly, it requires further research.

The structure of abstract impresses. It consists of brief information about the practical importance of the study, design, setting, subjects of the experiment, methods of the experiment divided into two parts, measures of sleep quality and refreshment, results on the differences between the experimental groups, and a conclusion which proves the harmful influence of caffeine on sleep.


The introduction leads the reader to the study. It explains the reason why this study is important and why this topic needs investigation. First of all, the authors mention that many adults consume caffeine beverages and foods every day. For some of them, this became an addiction. The researchers claim that caffeine beveragres have variousadvantages, for example, people drink it in order to improve alertness, mood and performance (Ho, Chung 2013). Even though, it is well known that caffeine disrupts sleep, the topic of caffeine abstinence remained without proper attention. Moreover, it is not about the coffee, but also about tea, including the healthful green tea. That is why the researchers decided to test whether the caffeine abstinence in the evening will improve the quality of sleep. The results are going to be useful for people with caffeine habits. In general, the introduction gives enough information about the issue and the previous studies, which prove the innovation of the idea to investigate abstinence of caffeine food. In addition, the researchers devote the part of the introduction to the previous findings of other studies on the main impacts of coffee and tea on the human body. For example, one of such studies examined the caffeine effects on physiological sleep tendency during night shifts and on daytime sleep, and the researchers found out that caffeine decreases sleep tendency (Muehlbach, 1995). In such a way, the study is devoted to the influence of caffeine on sleep. The research question is whether the abstinence of the component of food will improve the quality of sleep. The hypothesis that it will is logical, because if caffeine disrupts sleep, the abstinence of it will return the heavy sleep.

The authors also provide a literature review in the introduction. Many researches have previously studied the effect of caffeine on the human body, for example, coffee has a positive impact on some internals, on diabetes melittus, hepatitis B, Parkinson’s and Alzheimer’s diseases. According to other sources, the consumption of caffeine has also downsides, such as, rheumatoid arthritis, osteoporosis, epilepsy, postmenopausal problems, and other.

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The research is current and completely relevant. Because of the unlimited access to coffee, tea and chocolate, as well as the enormous popularity of these products, people get used, sometimes addicted, to them. People do not control the consumption of caffeine products, because it does not have immediate and obvious affects, so the consumers do not even think that it may harm.

The next part after the introduction is the section of methods. The authors used the experimental way of getting the results. They tested students divided into two groups, with and without caffeine consumption, during two weeks. Considering the topic and research question of the study, the method seems to be the most useful. It requires subjects. In this case, the researchers worked with young people from university. Previously, they completed the Pittsburgh Sleep Quality Index and provided information about their caffeine consumption during the last 6 months. The authors of an article provide a clear outline to describe the stages of experiment. According to this table, the first week was the period when all the research subjects consumed coffee and noted sleeping and waking up with the help of actigraphs. After the random assignment, the researchers divided them to caffeine and caffeine-free groups. The first group continued the same schedule, the second one – quitted it, but continued with actigraphs.

Talking about the sample, the requirements for the future research subjects were strict. The non-smokers, non-alcohol drinkers, non-caffeine consumers, pregnant and those who took medicines were excluded. This preparation proves the seriousness of the research on the basic level. It helps to find the answer to the research question in general. The procedure began after the recruitment of subjects. Firstly, the researchers agreed on the study with the ethics committee. Then, the subjects got complete information about the investigation. An important moment in the study was confidentiality. Only the researchers and co-researchers knew the information about the research subjects. However, all data was destroyed after the final results of the experiment. The authors of the article describe the process of this experiment. During these 14 days, the subjects could consume only caffeine products from the list by the research team. Moreover, they had to drink coffee at dinner. For the first week, all of them drank only pure coffee. After the division, one group continued this path, the other one stopped. The researchers underline again that the sleep was measured with an actigraph. In addition, the research subjects have got a reward for their participation in the experiment.

The researchers added the methods of calculation by using different measures, for example, Pittsburg Sleep Quality Index (PSQI), which was held at the beginning of the experiment, sleep log and wrist actigraph. The researchers highlight the importance of PSQI measure, explaining the data as this measure is a starting point of the data analysis. They used the sleep log during the experiment to measure the sleep quality and the level of refreshment. Finally, the wrist actigraph determined the sleep-wake parameters. In the following paragraph, the authors provide their analysis of this data collection.

The next section is devoted to the results, the most important part of the article. Here appears the information about the amount, gender and age of subjects, as well as their sleep condition before the experiment. People who do not drink coffee in the evening were identified as good sleepers. The researchers also describe the content of divided groups. They also note the use of Fisher’s Exact test, later the Wilcoxon test and Mann-Whitney U test, as the amount of subjects was small. To prove the results the researchers provide the tables with data on the study. The first table provides the characteristics and comparison of the subjects in each group. This data does not differ much. The second one proves the little difference in changes of sleep quality among the subjects of caffeine and caffeine-free groups in the middle of an experiment. The last table is the comparison of sleep quality on the last experimental day.

The penultimate section is devoted to the discussion. The authors explain why the experiment did not show any changes in the subjects’ sleep quality and time. As one of the main problems, they note the small sample. The second one is the dose moderation. The main mistake was that the subjects were good sleepers, so the abstinence did not influence them. The study does not solve this problem for bad sleepers. The researchers give a piece of advice.

This work is practical for those people who cannot imagine their lives without a cup of coffee or tea, or without chocolate, but have problems with sleep. The results of this research will help people to deal with the dilemma: caffeine or sleep, and will teach them to combine the favorite habit with their natural needs. Of course, this study also has important meaning for the development of clinical practice and system of health improvement. Moreover, this pilot study is the push to the further investigations. The results can be applied in theoretical knowledge, as well as a practical experience in real life. The importance of the study is also in the lack of hypothesis confirmation. This proves that the short period of coffee consumption does not disrupt sleep, and the short time abstinence does not improve the quality of sleep. Even though, good sleepers can continue with caffeine consumption, they have to remember that it is not recommended to drink coffee or tea during the last 6 hours before the sleep.

In general, the authors wrote the article in a clear and understandable manner. The complete information is noted and explained. The aim, the point and the procedure are clear enough to understand the process. The results are described briefly and simply. As an improvement and further investigation, it would be great to make such an experiment with other people who did not fit the requirements this time. This would be important for the complete understanding of the research question and would widen the investigation point. Moreover, it would be necessary to involve a larger amount of research subjects to the next study for the new results that would prove the previous ones or completely destroy the pilot findings. In addition, it would be useful to extend the duration of the experiment because if the caffeine influences the sleep for longer time, as it does with the caffeine addicted people, the longer time of “rehabilitation” is likely to show different results.


The article is interesting and provides useful information. The study investigated the relevant problem of caffeine abstinence, specifically its influence on sleep improvement. Even though, the results of the experiment did not show significant changes in the subjects’ sleep quality, the study has a great importance for further investigation, as the researchers already know the mistakes that they made during this pilot study, and people who drink coffee now know that the abstinence of caffeine consumption might not improve their sleep. Perhaps, the following researches will provide more information concerning this issue.