Objective: The objective of this study was to analyse the various environmental and behavioural factors affecting sleep quality among sixth-year medical students.
Methodology: Relevant articles were searched in PubMed, Medline, Springer, Elsevier, ScienceDirect, Cochrane Library, Google Scholar, and other websites. Data were collected using a self-administered questionnaire that included questions on risk factors affecting sleep. Descriptive and comparative analyses were performed to determine averages, frequencies, and relationships between the various studied variables. Statistical tests were conducted to compare groups based on the presence or absence of specific risk factors, consumption of stimulants before bedtime, doing physical exercise, having a bedtime routine, use of electronic devices, smoking, and environmental factors.
Results: In scientific articles, it was noted that using electronic devices before bedtime, smoking, not having a bedtime routine, sedentary behaviour, and the consumption of stimulants before bedtime are factors that contribute to sleep disorders. Explanations for these associations were also provided. In the survey conducted with 59 students, 11 students reported having sleep disorders; of these, 11 students with sleep disorders indicated that they used electronic devices before bedtime, and all 5 students who smoked reported experiencing sleep disorders.
Conclusion: This study identified significant associations between sleep disorders and several factors, including the use of electronic devices before bedtime and smoking.

Sleep disorders, Electronic devices, Smoking, Sleep quality, Hormones, Mood regulation, Immunity, Memory organization.

Sleep is a fundamental biological process essential for maintaining physical and mental health. It plays a crucial role in various physiological functions, including hormone regulation, immune response, and cognitive performance. Despite the well-documented benefits of sleep, many individuals, particularly medical students, suffer from sleep disorders due to various environmental and behavioural factors. This study aims to identify these factors and their impact on sleep quality among sixth-year medical students.[1,2]

The pineal gland is responsible for producing the hormone that regulates sleep, called melatonin. The suprachiasmatic nucleus (SCN) triggers the pineal gland to produce melatonin as daylight starts to fade. The hormone is released into the bloodstream starting at around 9 p.m. and continues to rise through the early part of the night. As this happens, you get sleepier and remain so until daylight prompts the SCN to wake the body.[3,4]

Sleep heals and repairs your heart and blood vessels. It helps support a healthy balance of the hormones that make you feel hungry (ghrelin) or full (leptin): When you don’t get enough sleep, your level of ghrelin goes up and your level of leptin goes down. This makes you feel hungrier than when you’re well-rested. It affects how your body reacts to insulin: Insulin is the hormone that controls your blood glucose (sugar) level. Sleep deficiency results in a higher-than-normal blood sugar level, which may raise your risk of diabetes. It supports healthy growth and development: Deep sleep triggers the body to release the hormone that promotes normal growth in children and teens. This hormone also boosts muscle mass and helps repair cells and tissues in children, teens, and adults. Sleep also plays a role in puberty and fertility. It affects your body’s ability to fight germs and sickness: Ongoing sleep deficiency can change the way your body’s natural defence against germs and sickness responds. For example, if you’re sleep deficient, you may have trouble fighting common infections. It decreases your risk of health problems, including heart disease, high blood pressure, obesity, and stroke.[5-7]

Sleep disorders (or sleep-wake disorders) involve problems with the quality, timing, and amount of sleep. To diagnose a person with a sleep disorder, the sleep difficulties must occur at least three nights a week for at least three months and cause significant distress or problems in important areas of the person’s daily functioning, such as work, school.[8]

The prevalence of sleep disorders in the general population ranges from 20–41.7%. The prevalence of sleep disorders in the United States follows a similar pattern, with 50–70 million U.S. adults impacted by a lack of sleep.[9]

Risks of insufficient sleep: The way you feel while you’re awake depends in part on what happens while you’re sleeping. Poor sleep affects hormones that influence cancer cells. Hormones released by the brain, such as cortisol and melatonin, are affected by the amount of sleep. Cortisol is related to stress and typically peaks at dawn, after hours of sleep, and declines throughout the day. It helps regulate the immune system, including the release of certain “natural killer” cells that help the body battle cancer.[10] Lack of sleep also may lead to microsleep. Microsleep refers to brief moments of sleep that happen when you’re normally awake.

Types of sleep disorders: The International Classification of Sleep Disorders (ICSD) categorizes sleep disorders based on the symptoms, how it affects a person (pathophysiology), and the body system it affects. The brand-new revision to the third edition, ICSD-3R includes the following categories:[11]

• Insomnia: difficulty falling and staying asleep.
• Sleep-related breathing disorders: breathing changes during sleep.
• Central disorders of hypersomnolence: trouble feeling alert during the day.
• Circadian rhythm sleep-wake disorders: the internal clock makes it difficult to fall asleep and wake up on time.
• Parasomnias: Physical actions or verbal expressions happen during sleep, like walking, talking, or eating.
• Sleep-related movement disorders: Physical movements or the urge to move make it difficult to fall asleep and/or stay asleep.

Risk factors for developing insomnia: Insomnia is defined as trouble falling asleep or staying asleep. It is the most common sleep disorder in the U.S. Worry, stress, and jet lag may cause short-term insomnia. Chronic, or long-term insomnia, may be caused by a range of conditions.[12,13] Including:

• Stress and anxiety
• Work late shifts.
• A symptom of a medical condition like heart disease, asthma, pain, or a nerve condition.
• A symptom of a mental health condition, like depression or anxiety disorder
• Genetic factors
• A side effect of medication.
• Working the night shift.
• Substance use before bedtime, such as caffeine or alcohol.
• Low levels of certain chemicals or minerals in the brain.
• An unknown cause.

Electronics and sleep: Electronic devices like smartphones, laptops, and TVs emit an artificial blue light that mimics sunshine. Sunlight signals the body to wake up. The optic nerve in the eye sends light and dark signals to a group of cells in the brain known as the SCN. Those signals tell the body’s internal clock when it’s time to wake up or go to sleep. When your body clock isn’t set right because of interference from blue light, the SCN can’t activate normal bodily functions and regulate hormones.[14]

Hormones and sleep: Melatonin, often called the sleep hormone, signals your brain that it’s time to sleep. It’s released in your blood in response to darkness. Melatonin production goes down as we age, which is one of the reasons why older people often experience insomnia. Cortisol is sometimes known as the stress hormone. It’s released when you experience stress or anxiety. High levels of this hormone in your blood can prevent you from falling asleep or staying asleep. Estrogen and progesterone. Although people of all sexes have estrogen and progesterone in their bodies, cisgender females have especially high levels. These hormones are involved in sleep regulation, although how isn’t well understood.[15] Levels of estrogen and progesterone go up during pregnancy and down during menopause. These natural hormonal fluctuations can affect sleep quality. Other hormones that can affect your sleep patterns include growth hormone, leptin (satiety hormone), and ghrelin (hunger hormone).

Study objectives: Analyse sleep habits and their relationship with various environmental and behavioral factors.

Study type: Cross-sectional observational survey.

Study population: The study population consists of 54 6th-year medical students from the epidemiology group at Mustapha Pacha University Hospital.

Data collection: Data were collected using a self-administered questionnaire that included questions on risk factors affecting sleep.

Descriptive and comparative analysis: Data were analysed to determine averages, frequencies, and relationships between the various studied variables. Statistical tests were conducted to compare groups based on the presence or absence of certain risk factors.

Average sleep duration: 

Table 1: Distribution of sleep duration among individuals with and without sleep disorders

Results

• Less than 7 hours: 7 with sleep disorder, 35 without.
• More than 7 hours: 4 with sleep disorder, 13 without.
• Odds Ratio: 0.65 (reduced odds of having a sleep disorder with less than 7 hours of sleep).
• Fisher exact test: p = 0.7132 (not significant).

Discussion
The odds ratio suggests that participants who sleep less than 7 hours have a lower likelihood of having a sleep disorder compared to those who sleep more than 7 hours. However, this result is not statistically significant (p > 0.05), indicating that the observed difference could be due to chance.

Sleep disorders and gender: 

Table 2: Distribution of sleep disorders among genders

Results

• Women: 7 with sleep disorder, 41 without.
• Men: 4 with sleep disorder, 7 without.
• Fisher exact test: p = 0.1909 (not significant).

Discussion
There is no statistically significant association between gender and the presence of sleep disorders (p > 0.05). This suggests that gender does not play a significant role in the likelihood of having a sleep disorder in this sample.

Consummation of Stimulants Before Bedtime:

Table 3: Consumption of stimulants before bedtime among individuals with and without sleep disorders

Results

• Yes: 2 with sleep disorder, 6 without.
• No: 9 with sleep disorder, 42 without.
• Odds Ratio: 1.56 (higher odds of having a sleep disorder with stimulant consumption).
• P-value: 0.668 (not significant).

Discussion
Although the odds ratio indicates a higher likelihood of having a sleep disorder with stimulant consumption before bedtime, the result is not statistically significant (p > 0.05). This suggests that stimulant consumption may not be a strong predictor of sleep disorders in this sample.

Physical exercise: 
About 40% of participants engage in physical exercise, primarily in the evening.

Table 4: Physical exercise and sedentary behavior among individuals with and without sleep disorders

Results

• Physical exercise: 3 with sleep disorder, 15 without.
• Sedentary behaviour: 8 with sleep disorder, 33 without.
• Odds Ratio: 0.66 (reduced odds with physical exercise).
• P-value: 0.573 (not significant).

Discussion
The odds ratio suggests that engaging in physical exercise at least twice a week is associated with lower odds of having a sleep disorder compared to sedentary behaviour. However, this association is not statistically significant (p > 0.05).

Bedtime routines: 

Table 5: Bedtime routines among individuals with and without sleep disorders

Results

• Bedtime routines: 3 with sleep disorder, 14 without.
• No bedtime routines: 8 with sleep disorder, 34 without.
• P-value: 0.279 (not significant).

Discussion
There is no significant association between having bedtime routines and the presence of sleep disorders
(p > 0.05). This indicates that bedtime routines may not significantly impact sleep disorders in this sample.

Use of electronic devices before bedtime: 
The use of electronic devices before bedtime is common among 94.8% of participants.

Table 6: Use of electronic devices before bedtime among individuals with and without sleep disorders

Results

• Use of electronic devices: 11 with sleep disorder, 44 without.
• No use of electronic devices: 0 with sleep disorder, 4 without.
• P-value: 0.018 (significant).

Discussion
There is a statistically significant association between the use of electronic devices before bedtime and the presence of sleep disorders (p < 0.05). This suggests that using electronic devices before bed is associated with a higher likelihood of having a sleep disorder.

Table 7: Smoking habits among individuals with and without sleep disorders

Results

• Smoke: 5 with sleep disorder, 0 without.
• No smoke: 6 with sleep disorder, 48 without.
• P-value: 0.002 (significant).

Discussion
The significant p-value indicates a strong association between smoking and the presence of sleep disorders (p < 0.05). Smokers are significantly more likely to have sleep disorders compared to non-smokers in this sample.

Environmental factors: 

Table 8: Environmental factors and sleep disorders

Results

• Disruptive environmental factors: 7 with sleep disorder, 34 without.
• No disruptive environmental factors: 4 with sleep disorder, 14 without.
• P-value: 0.061 (near-significant).

Discussion
There is a trend towards a significant association between disruptive environmental factors and sleep disorders (p = 0.061), but it does not reach the conventional alpha level of 0.05. This suggests that disruptive environmental factors may have some impact on sleep disorders, but further research is needed to confirm this.

Limitations
Small sample size: A small sample size reduces the power of the study and increases the margin of error, which can make the results less reliable and less generalizable to a larger population.

Self-reported data: The use of self-administered questionnaires can introduce bias, as participants may not accurately recall or may misreport their behaviours and experiences.

Cross-sectional design: Since the study is cross-sectional, it captures data at a single point in time, making it difficult to establish causality between the risk factors and sleep disorders.

Selection bias: The sample may not be representative of the entire population of sixth-year medical students, which can limit the generalizability of the findings.

Confounding variables: There may be other unmeasured factors that influence sleep quality, such as stress levels, academic workload, and personal health conditions.

The study finds significant associations between smoking, use of electronic devices before bedtime, and sleep disorders. Other factors, such as average sleep duration, consumption of stimulants before bedtime, physical exercise, bedtime routines, and disruptive environmental factors, did not show statistically significant associations in this sample. This study highlights the importance of understanding risk factors for sleep disorders and suggests areas for further research, particularly regarding the role of electronic devices and smoking.

The more we understand the phenomenon of sleep and its impact on the human body, the more motivated we become to identify factors that enhance sleep quality and closely monitor them. While hard work often extends into late hours, it is equally essential to prioritize our health.

I extend my gratitude to Dr. Ouchen and Dr. Guerchani for their valuable guidance and contributions to my academic journey.

Not reported

Belmecheri Roufaida
Department of Medicine
University of Algiers, Algeria
Email: belmecheriroufaida@gmail.com

The author contributed to the conceptualization, investigation, and data curation by acquiring and critically reviewing the selected articles and involved in the writing – original draft preparation and writing – review & editing to refine the manuscript.

Not applicable

Not reported

None

https://doi.org/10.63096/medtigo3084213

Belmecheri R. Study on Risk Factors Affecting Sleep. medtigo J Neurol Psychiatry. 2025;2(1):e3084213. doi:10.63096/medtigo3084213 Crossref