
==== Front
Rev Assoc Med Bras (1992)
Rev Assoc Med Bras (1992)
ramb
Revista da Associação Médica Brasileira
0104-4230
1806-9282
Associação Médica Brasileira

10.1590/1806-9282.20240635
00800
Commentary
Prevalence of sleep disorders and daytime sleepiness depends on many influencing factors that should be taken into account
https://orcid.org/0000-0003-2839-7305
Finsterer Josef 1 *
1 Neurology and Neurophysiology Center – Vienna, Austria.
*Corresponding author: fifigs1@yahoo.de
Conflicts of interest: the authors declare there is no conflicts of interest.

02 9 2024
2024
70 8 e2024063530 4 2024
20 5 2024
https://creativecommons.org/licenses/by/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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pmcDear Editor,

We read with interest Souza et al.'s article on a cross-sectional study of sleep quality and daytime sleepiness in 179 students at a private university between August 2021 and March 2022 using the Pittsburgh Sleeping Quality Index (PSQI) and the Epworth Sleepiness Scale (ESS) in the form of an electronic questionnaire 1 . According to the PSQI, 65% of students had poor sleep quality, with no difference between gender, BMI, and graduation category 1 . Students with a BMI >25 kg/m2 had longer sleep latency and shorter sleep duration than students with a lower BMI 1 . According to ESS, 44% of students had daytime sleepiness 1 . The study is impressive, but some points require discussion.

The first point is the use of an electronic questionnaire. Electronic questionnaires have the disadvantage that the correctness of the answers cannot be easily checked, and it is difficult to judge whether the addressee is actually the person who answered and whether the respondent was mentally capable of understanding the questions correctly and giving appropriate answers.

The second point is that various causes of sleep loss and daytime sleepiness were not taken into account. Sleep disorders can also be due to unusually high consumption of adrenergic stimulants (coffee, tea, cacao, cola, Red Bull, nicotine), acute or chronic stress, abuse of illegal drugs, alcohol addiction, unpleasant sleeping places (bright, noisy, increased humidity, not well tempered), unusually frequent use of electronic devices (laptop, tablet, cell phone), abuse of TV watching or computer work before going to bed, chronic cardiac disease, chronic muscle disease, endocrine disease, metabolic disease, and psychiatric disorder. Furthermore, it would have been mandatory to report the current medication of all included patients. We should also know how many of the students included were using illegal drugs, either stimulants (e.g., speed) or sedatives (e.g., cannabis).

A third point is that the study was obviously carried out during the pandemic. Therefore, it is imperative to rule out complications of SARS-CoV-3 infection 2 or SARS-CoV-2 vaccination 3 , including post-COVID-19 syndrome or long post-COVID-19 vaccination syndrome. We should know how many suffered from the SARS-CoV-2 infection and how many suffered from severe side effects after the SARS-CoV-2 vaccination.

A fourth point is that the number of females was significantly higher than that of men. This inequality can lead to bias.

A fifth point is that sleep quality can also depend on a person's social status and income. We should know whether the cohort could be divided into high- and low-income students and whether sleep quality and daytime sleepiness differed between high- and low-income students. It should also be reported whether academic performance differs between people with and without sleep disorders or daytime sleepiness.

In summary, the excellent study has limitations that make the results difficult to interpret. Removing these limitations could strengthen and support the study's message. Sleep quality and daytime sleepiness depend on numerous influencing factors that must be included in the analysis in order to make conclusive statements.

Funding: none.
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REFERENCES

1 Souza AKR Sandes RS Vasco RFV Albuquerque EVA Quality of sleep and excessive daytime sleepiness among medical students in a Brazilian private university Rev Assoc Med Bras (1992) 2024 70 3 e20231141 10.1590/1806-9282.20231141 38656002
2 Duong-Quy S Tang-Thi-Thao T Huynh-Truong-Anh D Hoang-Thi-Xuan H Nguyen-Van T Nguyen-Tuan A Sleep disorders in patients with severe COVID-19 treated in the intensive care unit: a real-life descriptive study in Vietnam Discov Med 2024 36 183 690 698 10.24976/Discov.Med.202436183.65 38665018
3 Mahamid A Bornstein RJ Amir H Pfizer/BioNTech SARS-CoV-2 vaccine as a potential trigger for the development of narcolepsy: a case report J Clin Sleep Med 2022 18 10 2503 2506 10.5664/jcsm.10134 35733336
