Collaborative authorship, listed alphabetically by surname.

Abstract

Insomnia is a sleep disorder that causes difficulty in falling asleep and staying asleep. Adolescents are especially vulnerable due to major psychological, physiological and social changes during development. This paper examines why adolescents can experience insomnia despite high levels of physical exhaustion during the day, and the psychological, physiological and environmental factors that contribute to sleep disruption. Physiological factors could involve sudden changes in the body before bed that prevent sleep, like cortisol increase and even eating ultra-processed foods; environmental factors could be screens before bed, noise, light or a bad sleep schedule in general; and psychological factors could be general stress, pre-sleep arousal and anxiety/depressive symptoms. Ultimately, insufficient sleep can lead to emotional instability, daytime fatigue, bad memory and decision-making, and more. In teenagers, this could lead to a suffering academic performance and difficulty living day-to-day life.

Introduction

Insomnia is a common sleep disorder characterised by difficulty falling asleep, staying asleep or getting enough sleep. In adolescents, this could be a major concern if these problems continue to interfere with daily life. The total burden of insomnia affects health challenges, productivity and sleep. Insomnia disorder can eventually lead to difficulties with attention, memorisation and concentration. Persistent or chronic insomnia is a sleep disorder that occurs over a long period rather than only occasionally. However, a person being physically exhausted does not mean their mind or body can receive a restful sleep.

Sleep depends on the mental and emotional state of the brain, rather than simply a physically tired body. However, several factors affect insomnia: psychological, physiological and environmental factors. Physiological factors involve sudden changes in the body that prevent the body from sleeping. Environmental factors include screen time before bed, noise, light or a bad sleep schedule that affects the body’s ability to rest. These factors are extremely important to examine in adolescence because teenagers experience sudden changes in life, such as physical, emotional and social changes. Adolescents may have demanding school schedules that contribute to the lack of sleep one may be receiving. Teenagers have extracurricular activities, social responsibilities, exposure to technology and screen time. These influences make healthy sleep more difficult to achieve. Comprehending why insomnia occurs during adolescence is important because sleep plays a key role in mood, social being and overall wellness. 

The teenage years, a period of major neurological and physiological development, play a crucial role in the transition into adulthood. Major neurological changes occur, including the development of the prefrontal cortex – which is involved in decision-making, attention, planning and emotional regulation (Galván, 2020) – hormonal changes, physical growth and changes in sleep regulation. The biological clock shifts later during puberty, meaning teenagers naturally tend to become sleepy later at night (Crowley et al., 2018). This can conflict with early school schedules and contribute to disrupted sleep or insomnia. Sufficient sleep is fundamental during these years to support brain development, academic performance, physical growth, emotional regulation and physical health (Galván, 2020; Illingworth, 2020). 

Insufficient or disruption of sleeping hours can lead to emotional instability, daytime sleepiness, fatigue, low energy and reduced motivation, concentration, memory and decision-making (Illingworth, 2020; Zhang et al., 2022). This leads to difficulty processing and retaining new information, subsequently affecting academic performance (Galván, 2020; Zhang et al., 2022). A teenager can feel extremely tired but still be unable to fall asleep. Understanding this complex dilemma is important not only to determine factors in our daily lives that may be affecting our sleep or its quality, but also to help researchers and healthcare professionals develop more appropriate interventions, rather than treating tiredness alone. Therefore, this review aims to understand the psychological, physiological and environmental factors that contribute to persistent insomnia in adolescents despite high levels of daytime physical exhaustion.

Methodology

A literature search was conducted using PubMed to identify studies with factors contributing to persistent insomnia among teenagers 13-18 years of age experiencing high levels of daytime physical exhaustion. The search strategy used MeSH and title/abstract keywords related to four main concepts: adolescence; insomnia and/or sleep quality; physical fatigue and/or exhaustion; and psychological, physiological or environmental factors. Search terms included combinations of terms including: adolescent, insomnia, sleep quality, fatigue, physical exhaustion, daytime fatigue, anxiety, stress, circadian, hyperarousal, screen time, noise, light and school. Studies published in the past decade were considered up to date.

Table 1: Inclusion and Exclusion Criteria.

The studies with test participants of teenage age (13-20 years old) suffering from daytime physical exhaustion were selected for inclusion in this review. The studies had to refer to persistent insomnia or include psychological, physiological or environmental risk factors for insomnia. Eligible study types included: systematic reviews, literature reviews, meta-analyses, clinical trials and observational studies. Only studies written originally in English and with the full text accessible were included. Studies involving populations outside the age range, neurological disorders that could act as conflicting factors, unrelated sleep disorders, animal studies, news articles, opinion pieces and studies without full-text access were excluded.

Eight reviewers participated in the research to complete this literature study. These eight independent reviewers were assigned to assess specific subfactors relevant to the research question. The reviewers focused on three areas: psychological triggers, environmental drivers and physiological mechanisms. Each reviewer was assigned a specific subfactor to research as their domain. Eventually, the distribution was as follows: three reviewers focusing on environmental subfactors; three reviewers focusing on psychological subfactors; and two reviewers focusing on physiological subfactors. For initial screening, the reviewers independently screened titles and abstracts within their assigned domains to determine relevance to the research question and eligibility criteria. Following screening, nine studies were selected for the final literature review. The reviewers then reviewed the full texts of the selected studies. Disagreements or ambiguities regarding study inclusion were discussed among the reviewers and resolved through consensus. 

Data was extracted from the final set of selected studies using a standardised data extraction matrix. The matrix was structured to ensure uniform data capture across all types of studies. Each reviewer had tested the matrix prior to the research by doing a trial consisting of three articles. The extracted information included title, journal, author(s), year, specific health outcome studied, environmental exposure metric, primary biological or clinical findings relevant to the research question, vulnerable sub-populations identified and underlying biological or physiological mechanisms. Key study limitations, gaps and further research recommended by the authors were also documented. Methodological quality and the risk of bias were qualitatively evaluated for each included study by the reviewers. This assessment evaluated sample area, sample size, generalisability, selection of participants, self-reported data or unreliable surveying, subjectivity, methodology and search strategies to determine overall study reliability. A narrative synthesis was used to summarise, group and contrast the findings across all included studies.

Results

I. Environmental Synthesis

The papers discussing the impact of food and nutrition found that severe food insecurity (FI) and lack of nutrition increases sleep disturbance in adolescents (Wang, 2021; Davis et al., 2021). The increase of sleep disturbances leads to less sleeping hours and disrupts the circadian rhythm, which Gardani et al. (2022) showed was exacerbated by other mental health problems and stress caused by academic pressure. The circadian misalignment, which is the “discrepancy between activity/sleep schedules on school/work days and free days” (Caliandro et al., 2021), can be caused by sleep disturbances as well as sleeping and waking hours that are either ahead or behind the body’s natural circadian rhythm. In adolescents, this is usually related to either early hours for school or the use of light-emitting devices at late hours (Gardani et al., 2022), with students sleeping less hours and experiencing more sleep disturbances, alongside other associated behaviours to social jetlag, including unhealthy eating patterns. For adolescents already experiencing difficulties with food through food insecurity or eating disorders, the added effects of insomnia can feed into a negative feedback loop and exacerbate symptoms.

Throughout various studies, it was found that social environments have a significant influence on sleep health. Students, specifically undergraduate students, are faced with countless stressors that worsen sleep quality. Expectations such as the increasing cost of living and tuition fees, transitioning to university level study, the opportunity for increased alcohol intake and possible substance abuse, and the experience of overlapping deadlines and late working hours create stress on adolescents and disturb their circadian rhythm.

II. Psychological Synthesis

These studies focused on how psychological factors affected insomnia in adolescents despite physical tiredness such as stress, anxiety, depression or cognitive arousal (an overactive mind with racing or worrying thoughts). Kater et al. (2023) found that adolescents with high sleep reactivity (how easily sleep is disturbed) were 2.95 times more likely to have insomnia while also having higher levels of pre-sleep arousal, stress and negative thoughts about sleep.

Similarly, Heath et al. (2018) found that somatic arousal (physical tension or alertness) was linked to taking longer to fall asleep. Sleep-related thoughts were also linked to sleep misperception (thinking it took longer to fall asleep than it actually did). Additionally, Liu et al. (2022) found strong links between insomnia, daytime sleepiness and depression, with insomnia linked to 10-14 times greater odds of daytime sleepiness and 5-9 times greater odds of depressive symptoms. Finally, Yang et al. (2023) found that stress, insomnia and anxiety/depressive symptoms were all linked in both directions creating a bidirectional relationship, meaning these factors may affect each other over time. This is indicated with students with chronic insomnia showing a stronger link  to psychological symptoms (12.65 vs. 9.84, p < 0.001).

Dresp-Langley and Hutt (2022) found a link between digital addiction and insomnia/depression with the 2025 scoping review also finding that adolescents with depression were more likely to experience sleep disturbances. Overall, these studies showed that stress, psychological symptoms and increased cognitive arousal were linked to poorer sleep, which may contribute to sleep problems even when adolescents experience daytime tiredness.

III. Physiological Synthesis

Across the three studies, sleep disturbances were associated with multiple physiological processes, suggesting that insomnia cannot be explained by one single biological mechanism. One recurring factor was the relationship between psychological stress and sleep. In one meta-analysis, Dreessle et al. (2022) explained how stress is related to higher levels of cortisol, leading to hyperarousal, the most direct cause of insomnia and other sleep disorders (Dressle et al., 2022). However, this finding was not consistent across studies. One study researched adolescents and young adults with ASD and their sleep patterns. This paper found no significant differences in cortisol and melatonin levels between ASD and typical development participants (Goldman et al., 2017). Another paper found that ultra-processed food may contribute to insomnia because of its lack of natural melatonin (Pourmotabbed et al., 2024). These findings suggest that although cortisol and melatonin levels may contribute to sleep health in some individuals, it is not a reliable explanation across different populations. 

The studies also identified other potential physiological factors. The association between ultra-processed food intake and insomnia risk suggests that nutritional and metabolic pathways could lead to insomnia. Possible mechanisms include differences in nutrient availability, glycemic load and disruption of the gut microbiome. Together, these findings indicate that sleep regulation could be influenced by stress-related hormonal activity, sleep-wake regulation and metabolic processes. However, limitations across studies, including small sample size, inconsistent cortisol measurement, classification of UPF and cross sectional study designs, make it difficult to generalise and establish a direct physiological cause of insomnia.

Critical Discussion

I. Environmental

An evaluation of the environmental findings suggest that adolescent insomnia is heavily affected by socioeconomic and structural constraints present in adolescents’ lives, rather than individual behaviour towards not wanting to sleep. Primary findings show that socioeconomic conditions, particularly food insecurity and poor housing conditions serve as adverse environmental conditions according to Wang (2021). Institutional environments such as school and work put pressure on adolescents. Academic stress, tuition fees, overlapping deadlines, school burnout and early school starting time degrade sleep quality and lead to sleep disorders such as insomnia. Early schedules create a conflict between the circadian rhythm, causing misalignment in the physiological system. Physically demanding training and high workload such as back-to-back athletic games worsen the sleep patterns of young athletes, leading to insomnia (Davis et al., 2022) Therefore, adolescents experience social jetlag, where society rules work against their physiology.

However, methodological limitations exist in the literature. A major limitation is the reliance on self-reported questionnaires rather than employing objective measurements in the studies of Wang (2021) and Philips et al. (2020) which introduces the recall bias. The study of Wang (2021) was cross-sectional, therefore the association between food insecurity and sleep disturbance remains uncertain. Philips et al. (2020) also used a subjective definition and cited studies only in English which creates potential biases. Furthermore, Gardani et al. (2022) reported high heterogeneity in their meta analyses, which suggests that the differences in participant demographics limit the generalisability of the findings.

II. Psychological

The findings suggest that persistent insomnia in adolescents may be driven by psychological/behavioural factors, not just physical tiredness. Across the literature, stress, pre-sleep arousal, anxiety/depressive symptoms and daytime sleepiness appear to interact. Kater et al. (2023) found that adolescents with high sleep reactivity showed greater stress vulnerability and pre-sleep-arousal, while Heath et al. (2018) found that somatic-arousal was associated with objectively longer sleep-onset-latency. Together, these findings suggest that sleep pressure from daytime exhaustion can coexist with cognitive/physiological activation, preventing sleep initiation.

The longitudinal studies suggest that these factors may reinforce one another over time, contributing to persistent insomnia. Liu et al. (2022) found bidirectional relationships between insomnia and daytime sleepiness, while Yang et al. (2023) found reciprocal relationships between life stress, insomnia and anxiety/depressive symptoms. Therefore, exhaustion may not only result from insomnia but also maintain it through daytime-sleeping and increased psychological distress. This interpretation is strengthened by Li et al. (2024) where fatigue, restlessness and worry were central symptoms connecting depression, anxiety and insomnia (although it involved college students rather than adolescents, limiting direct generalisation).

However, reliance on self-reported measures may limit the findings, as Heath et al. (2018) found that perceived sleep difficulties do not always reflect objective sleep impairment. Kater et al. (2023) also used a relatively small sample and longitudinal assessments may miss short-term changes. Overall, the evidence supports a multifactorial process in which psychological arousal overrides physical sleepiness, explaining why adolescents remain unable to sleep despite exhaustion. Future research should combine objective sleep measures with repeated assessments of stress, cognition, digital behaviour and physiological arousal.

III. Physiological

Research supports the idea that psychological factors may influence persistent insomnia in adolescents, even if patients are physically exhausted during the day. Dressler et al. (2022) found that individuals with chronic insomnia had slightly elevated levels of cortisol during non-sleeping hours and that these levels increased with lack of sleep. When a person experiences stress, the body’s cortisol levels gradually increase, which can disturb sleep. However, the study may contain some confounding variables. Cortisol was measured at different times/methods in different studies, and the process of taking blood can also increase cortisol levels with individuals that may have a fear of needles. Because of this, the study shows a connection between cortisol and insomnia but does not give definitive proof that stress causes insomnia.

Goldman et al. (2017) found that adolescents on the autism spectrum took longer to fall asleep and experienced lower sleep quality. There were no noticeable differences in cortisol or melatonin levels compared to the control group. This implies that hormones may not have a strong relation to insomnia in adolescents. Other factors may also play a role, such as anxiety. Purmotabbed et al. (2024) found that increased levels of eating ultra-processed foods was linked to insomnia. Although this study mainly focuses on physical effects, it shows how everyday behaviours can affect the body and sleep. These studies give reason to believe that insomnia is likely caused by a multitude of factors working together, rather than physical exhaustion alone.

Conclusion

The combined effects of psychological, environmental and physiological factors appear to contribute to insomnia in adolescents despite being  physically tired during the day. Adolescents who are physically tired can still remain mentally alert because of stress, anxiety, depression and cognitive arousal which can inhibit sleep. Additionally, environmental factors, such as academic pressure, early school schedules and digital technology use, may also lead to increased stress and disturb sleep patterns. Physiological changes during this developmental period or other hormonal fluctuations such as the stress hormones can affect sleep regulation. These factors can then interfere with normal sleep patterns in adolescence, leading to persistent insomnia.

Future studies should examine how cognitive arousal, stress, physical exhaustion, sleep pressure, circadian rhythms and sleep-related behaviours interact. Larger and more diverse samples could also determine whether these relationships vary across countries, socioeconomic groups and developmental stages. Intervention studies should test whether reducing pre-sleep arousal, treating stress and insomnia together, or changing sleep-related behaviours can interrupt the cycle of poor sleep and psychological distress. 

Alnawwar, M. A., Alraddadi, M. I., Algethmi, R. A., Salem, G. A., Salem, M. A., & Alharbi, A. A. (2023). The effect of physical activity on sleep quality and sleep disorder: A systematic review. Cureus, 15(8).

Bacaro, V., Carpentier, L., & Crocetti, E. (2023). Sleep Well, Study Well: A Systematic Review of Longitudinal Studies on the Interplay between Sleep and School Experience in Adolescence. International Journal of Environmental Research and Public Health, 20(6), 4829.

CSMA (2025) Fatigue vs. Sleepiness: Why You’re Still Tired After a Full Night’s Sleep, Comprehensive Sleep Medicine Association [online]. <https://www.csma.clinic/post/fatigue-vs-sleepiness>

Dressle, R. J., Feige, B., Spiegelhalder, K., Schmucker, C., Benz, F., Mey, N. C., & Riemann, D. (2022). HPA axis activity in patients with chronic insomnia: A systematic review and meta-analysis of case-control studies. Sleep Medicine Reviews, 62, 101588.

Fernandez-Mendoza, J., Baker, J. H., Vgontzas, A. N., Gaines, J., Liao, D., & Bixler, E. O. (2017). Insomnia symptoms with objective short sleep duration are associated with systemic inflammation in adolescents. Brain, Behavior, and Immunity, 61, 110–116.

Fernandez-Mendoza, J., Li, Y., Vgontzas, A. N., Fang, J., Gaines, J., Calhoun, S. L., Liao, D., & Bixler, E. O. (2016). Insomnia is Associated with Cortical Hyperarousal as Early as Adolescence. Sleep, 39(5), 1029–1036.

Gardani, M., Bradford, D. R. R., Russell, K., Allan, S., Beattie, L., Ellis, J., & Akram, U. (2022). A systematic review and meta-analysis of poor sleep, insomnia symptoms and stress in undergraduate students. Sleep Medicine Reviews, 61, 101565.

Goldman, S. E., Alder, M. L., Burgess, H. J., Corbett, B. A., Hundley, R., Wofford, D., Fawkes, D. B., Wang, L., Laudenslager, M. L., & Malow, B. A. (2017). Characterizing Sleep in Adolescents and Adults with Autism Spectrum Disorders. Journal of Autism and Developmental Disorders, 47(6), 1682–1695.

Heath, M., Johnston, A., Dohnt, H., Short, M., & Gradisar, M. (2018). The role of pre-sleep cognitions in adolescent sleep-onset problems. Sleep Medicine, 46, 117–121.

Kater, M.-J., Werner, A., Schlarb, A. A., & Lohaus, A. (2023). Sleep Reactivity and Related Factors in Adolescence: An Increased Risk for Insomnia? A Longitudinal Assessment. Nature and science of sleep, 15, 207–216.

Kaur, H., Spurling, B. C., & Bollu, P. C. (2023). Chronic Insomnia (PubMed: StatPearls Publishing).

Kids Health (2024) Insomnia in Teens: What Parents Should Know (for Parents). Kidshealth.org [online]. <https://kidshealth.org/en/parents/insomnia-teens.html>

Liu, X., Yang, Y., Liu, Z., & Jia, C. (2022). Associations between Insomnia, Daytime Sleepiness, and Depressive Symptoms in Adolescents: A Three-Wave Longitudinal Study. Journal of clinical medicine, 11(23), 6912.

Phillips, S. R., Johnson, A., Shirey, M. R., & Rice, M. (2020). Sleep Quality in School-Aged Children: A Concept Analysis. Journal of Pediatric Nursing, 52, 54–63.

Pourmotabbed, A., Awlqadr, F. H., Mehrabani, S., Babaei, A., Wong, A., Ghoreishy, S. M., Talebi, S., Kermani, M. A. H., Jalili, F., Moradi, S., Bagheri, R., & Dutheil, F. (2024). Ultra-Processed Food Intake and Risk of Insomnia: A Systematic Review and Meta-Analysis. Nutrients, 16(21), 3767.

Wang, Q. (2021). Food Insecurity and Sleep Disturbance Among 223,561 Adolescents: A Multi-Country Analysis of Cross-Sectional Surveys. Frontiers in public health, 9, 693544.

Wilson, D. A., Sullivan, R. M., Smiley, J. F., Saito, M., & Raineki, C. (2024). Developmental alcohol exposure is exhausting: Sleep and the enduring consequences of alcohol exposure during development. Neuroscience and biobehavioral reviews, 158, 105567.

Yang, Y., Liu, X., Liu, Z.-Z., Tein, J.-Y., & Jia, C.-X. (2023). Life stress, insomnia, and anxiety/depressive symptoms in adolescents: A three-wave longitudinal study. Journal of Affective Disorders, 322, 91–98.

de Zambotti, M., Goldstone, A., Colrain, I. M., & Baker, F. C. (2018). Insomnia disorder in adolescence: Diagnosis, impact, and treatment. Sleep Medicine Reviews, 39(39), 12–24.