Isolated and sleepless, from pandemic victims to those of "social jet lag"

Editorial Note

This article was previously published and has been updated according to scientific and divulgative criteria. It is for informational purposes only and does not replace individual medical advice. For persistent doubts or symptoms, consult your doctor.

IN BRIEF

• During the pandemic, many people reported a worsening of sleep quality and changes in their sleep-wake rhythm.
• Sleep deprivation or fragmentation is associated with reduced effectiveness of the immune response and greater vulnerability to infections.
• Evening use of light-emitting screens (blue light) and binge-watching are correlated with worsening sleep and delays in the circadian rhythm.
• Melatonin can help regulate the sleep-wake rhythm in some situations, but evidence on its immunomodulatory or protective action against specific infections is limited and inconclusive.
• Practical recommendations aim to improve sleep regularity and sleep hygiene, without replacing personalized clinical care.

Abstract: what does science say?

The central theme is the increase in sleep disorders in response to social and environmental events (e.g., lockdown, smart working, reduction of social cues), a phenomenon described as "social jet lag." Observational and experimental evidence indicates that short or fragmented sleep reduces the effectiveness of immune defenses and the response to some vaccinations; furthermore, evening exposure to light sources with a high blue component alters melatonin secretion and delays sleep. Studies conducted during the pandemic period show a widespread increase in insomnia and changes in sleep timing. The most robust intervention remains the regularization of rhythms (fixed sleep/wake times, sleep hygiene, reduction of evening light exposure); the use of melatonin as a tool to realign the rhythm is possible but requires clinical evaluation. The available evidence is predominantly observational or derived from experimental studies with limited samples; therefore, caution is needed in interpretation and generalization.

MAIN SECTION

What is "social jet lag" and why has it increased?

"Social jet lag" refers to the discrepancy between an individual's biological rhythm and the demands of social or work life. Even without traveling across time zones, sudden changes in routine (working from home, travel restrictions, changes in social rhythms) can produce alterations similar to those of jet lag: delayed sleep onset, more frequent awakenings, and non-restorative sleep. During periods of isolation (e.g., lockdown), many people reported later and more variable sleep patterns compared to the preceding period, with an increase in cases of reactive insomnia and impaired daytime performance [4]. These changes can be explained by the loss of external cues (natural light, commuter schedules, eating rhythms) that normally synchronize the biological clock, and by increased exposure to electronic stimuli in the evening, which delays the nocturnal secretion of melatonin [6].

What evidence links sleep to immune function?

Clinical and experimental literature shows that the quantity and quality of sleep influence various aspects of immune defense. Studies with controlled virus exposure have observed that subjects with short or inefficient sleep are more susceptible to respiratory infections [1][2]. Reviews and specific works on the relationship between sleep and vaccine response indicate that a lack of sleep around the time of vaccination can reduce antibody titers measured weeks or months later [7]. Proposed mechanisms include alterations in cytokine secretion, lymphocyte function, and natural killer cell activity; however, the complexity of the systems and individual variability necessitate caution in inferring simple causal links.

PRACTICAL SECTION

What does this mean in practice?

The evidence suggests that maintaining a regular routine and paying attention to sleep hygiene can have benefits both on the quality of rest and, indirectly, on the capacity for immune response. Small practical changes—setting consistent bedtimes and wake-up times, limiting screen exposure in the 1–2 hours before sleep, creating a dark and comfortable resting environment—contribute to consolidating the circadian rhythm and facilitating sleep onset. For those with persistent insomnia or sleep disorders that interfere with daily functioning, it is advisable to consult a sleep professional or their doctor for a targeted evaluation. The use of melatonin as an aid to regulate the biological clock is a possibility, but it must be evaluated on a case-by-case basis and is not a universal solution or a cure for complex health problems.

Late nights and the immune response

Epidemiological and experimental evidence

Both observational and experimental research correlates short or fragmented sleep with a higher risk of infectious diseases and an attenuated vaccine response. Laboratory studies and analyses of population samples show consistency on this point: for example, experimental studies with viral challenge have documented a higher probability of developing symptoms in subjects with insufficient sleep [1][2]. At the population level, systematic reviews and meta-analyses conducted in the context of the pandemic identify a generalized increase in sleep disorders, with possible repercussions on public health [4]. These results do not prove an exclusive cause-and-effect relationship, but indicate consistent biological plausibility and the need for public health interventions aimed at sleep well-being.

How much duration matters and when it depends on context

There is no magic threshold valid for everyone; however, most studies report increasing risks for those who sleep less than six to seven hours per night, especially if the deprivation is chronic. The effect on the immune response appears to depend on the duration and intensity of deprivation, sex, age, and pre-existing medical conditions; furthermore, the time window relative to events such as vaccination can be particularly relevant [7]. This means that the benefits of corrective measures can vary based on individual and temporal context.

Binge-watching, screens, and circadian rhythm

Behaviors that emerged during lockdown

During periods of social restriction, many people increased the time spent in front of screens and on-demand content. Studies conducted during the acute phase of the pandemic documented a consistent increase in binge-watching behaviors, with high percentages in some regional contexts and correlations with boredom, stress, and loneliness [3]. These behaviors can prolong exposure to light stimuli and delay sleep onset, reducing overall sleep quality.

Effect of artificial light and blue light

Exposure to artificial light in the evening, particularly to blue wavelengths emitted by many screens, suppresses melatonin secretion and delays sleep onset, with measurable effects on circadian rhythms and morning alertness [6]. Controlled experiments have shown that evening use of light-emitting devices can reduce sleepiness and delay biological timing, suggesting that limiting the use of these devices in the hours before bedtime is plausibly useful for promoting sleep.

Melatonin: role, benefits, and limitations

Mechanisms and practical applications

Melatonin is a hormone produced by the pineal gland that signals the arrival of night to the circadian system; melatonin supplements are used to facilitate the realignment of the sleep-wake rhythm, for example in cases of jet lag, shift work, or delayed sleep. Experimental evidence indicates that appropriate dosages and correct timing can help reduce sleep latency and improve sleep efficiency in some populations. However, individual response varies, and use should be evaluated by a healthcare professional when it comes to prolonged therapies or patients with comorbidities.

Melatonin and immunity: what we know

Some studies suggest immunomodulatory roles for melatonin in experimental models, but direct clinical evidence on melatonin's ability to protect against specific infections or consistently improve clinical outcomes is limited. Recent reviews emphasize that the available data do not allow for a direct and confirmed protective effect in the clinical setting against infections such as SARS-CoV-2; therefore, any interpretation must be cautious and contextualized [8].

Limitations of the evidence

It is important to distinguish between observed associations and causal evidence. Much research on sleep during the pandemic is based on observational studies or surveys that detect correlations but do not prove causality. Experimental studies on vaccines and sleep deprivation provide mechanistic clues, but often involve limited and specific samples (young adults, healthy volunteers), so generalizability is restricted [7]. There are also methodological limitations: self-reported sleep measures may differ from objective ones (actigraphy); the heterogeneity of immune measures and follow-up times complicates interpretation. Finally, confounding factors (psychological stress, physical activity, diet, medication use) can influence both sleep and immunity and make it difficult to isolate the exclusive effect of sleep [4][5].

Key takeaways

1. Regular and quality sleep is an important determinant for general well-being and plausibly influences the immune response.
2. Behaviors that emerged during the pandemic (binge-watching, evening screen use) are associated with worsening sleep and circadian delays.
3. Evening exposure to blue light reduces melatonin secretion and can hinder sleep onset; reducing its use in the hours before sleep is advisable as a hygienic measure.
4. Melatonin can be useful for realigning the sleep-wake rhythm in specific situations, but evidence on direct immune benefits is limited and not definitive.
5. The available evidence is partly observational and partly experimental; for individual therapeutic indications, consult a doctor.

Editorial conclusion

The social and behavioral changes that occurred during the pandemic have amplified problems already present in modern society: misalignment of rhythms, prolonged screen exposure, and an increase in behaviors that can compromise sleep. Scientific literature offers elements to believe that protecting and regularizing sleep is a relevant goal not only for psychophysical well-being but also for immune resilience at individual and collective levels. The most robust strategies remain non-pharmacological: regular routines, reduction of evening light exposure, an adequate resting environment, and, if necessary, clinical evaluation for targeted interventions. Pharmacological or integrative solutions, such as melatonin, have a role but require informed choices and health surveillance. Interpretive caution and personalization remain guiding criteria for integrating science into daily practice.

Editorial Note

Article updated following transparency and scientific validation criteria; the cited sources are peer-reviewed and listed in the "Scientific Research" section. The text is for informational purposes only and does not replace personalized medical advice.

SCIENTIFIC RESEARCH

The following research has been selected to support the claims in the article. For each entry, the reference with verified DOI is provided.

1. Cohen S, Doyle WJ, Alper CM, Janicki-Deverts D, Turner RB. Sleep habits and susceptibility to the common cold. Arch Intern Med. 2009;169(1):62–67. https://doi.org/10.1001/archinternmed.2008.505
2. Prather AA, Janicki-Deverts D, Hall M, Cohen S. Behaviorally assessed sleep and susceptibility to the common cold. Sleep. 2015;38(9):1353–1359. https://doi.org/10.5665/sleep.4968
3. Singh R, Sharma D, et al. Binge watching behavior during COVID‑19 pandemic: A cross‑sectional, cross‑national online survey. Psychiatry Res. 2020;289:113089. https://doi.org/10.1016/j.psychres.2020.113089
4. Systematic review: Sleep disturbances during the COVID‑19 pandemic: a systematic review, meta‑analysis and meta‑regression. Sleep Med Rev. 2022; [article]. https://doi.org/10.1016/j.smrv.2022.101591
5. Sleep Deprivation, Immune Suppression and SARS‑CoV‑2 Infection. Int J Environ Res Public Health. 2022;19(2):904. https://doi.org/10.3390/ijerph19020904
6. Chang AM, Aeschbach D, Duffy JF, Czeisler CA. Evening use of light‑emitting eReaders negatively affects sleep, circadian timing, and next‑morning alertness. Proc Natl Acad Sci U S A. 2015;112(4):1232–1237. https://doi.org/10.1073/pnas.1418490112
7. Spiegel K, Rey A, et al. A meta‑analysis of the associations between insufficient sleep duration and antibody response to vaccination. Curr Biol. 2023;33(5):998–1005.e2. https://doi.org/10.1016/j.cub.2023.02.017
8. Frontiers review: Sleep, Circadian Health and Melatonin for Mitigating COVID‑19 and Optimizing Vaccine Efficacy. Front Neurosci. 2021; https://doi.org/10.3389/fnins.2021.711605

[Internal DOI validation checklist: all listed entries have been verified as resolvable DOIs and pertinent to the topic discussed before publication]