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The science behind Unslouch breaks

This page explains why the app does what it does and which research stands behind it. For each part of the body: why it matters, what the app does, what studies show, and when to see a doctor.

How we chose

  • We relied on systematic reviews, meta-analyses, randomised trials and guidance from professional bodies (WHO, American Academy of Ophthalmology, OSHA). Where nothing better exists we cite small individual studies and say so.
  • The evidence is uneven. There is a lot of data on the benefits of movement and the harm of long sitting. There is little data on how often to take breaks or which exercises work best: studies are small, short and often have no control group. We point this out where it applies.
  • We write “reduces fatigue” and “reduces discomfort”, never “treats” or “prevents”. The app helps you avoid sitting too long. It does not treat any disease.
  • Figures were checked against abstracts and full texts. Where a number comes from a secondary source and we have not seen it in the original, we say so.

This is not medical advice. If something hurts, does not go away or gets in the way of your life, see a doctor. Do the exercises without pain: if it hurts, stop.

Eyes

Why

When we look at a screen we blink two to three times less often: about 5-7 times a minute instead of the usual 15. Many blinks are incomplete, the lid does not close fully. The tear film dries out, which causes dryness, burning and a gritty feeling. The second source of fatigue is the muscle that focuses the eye up close: it works for hours without rest. Looking into the distance lets it relax.

What the app does

  • Every 20 minutes it suggests looking into the distance, more than 6 metres (20 feet) away, for 20 seconds.
  • Some breaks include a lid exercise: slowly close your eyes, gently squeeze the lids, open.
  • Every 5 minutes the screen edges darken for a second as a cue to blink. No windows, no buttons.

What studies show

  • American Academy of Ophthalmology (AAO). People blink 5-7 times a minute at screens instead of about 15. Recommends looking into the distance regularly, artificial tears for dryness, screen at about arm’s length. The exact rule, every 20 minutes looking 20 seconds at something more than 6 metres (20 feet) away, is in the AAO article on blue-light glasses, which also says the Academy does not recommend special eyewear for computer use. https://www.aao.org/eye-health/tips-prevention/computer-usage ; https://www.aao.org/eye-health/tips-prevention/are-computer-glasses-worth-it
  • American Optometric Association (AOA). Screen 50-70 cm away, centre of the screen 15-20° below eye level, breaks, vision correction when needed. https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/computer-vision-syndrome
  • Sheppard & Wolffsohn, 2018, BMJ Open Ophthalmology 3:e000146. Review: digital eye strain affects roughly half of computer users or more. Breaks, proper vision correction and dry eye care help. doi:10.1136/bmjophth-2018-000146
  • Talens-Estarelles et al., 2023, Contact Lens & Anterior Eye 46(2):101744. 29 symptomatic users ran reminder software for distance breaks for two weeks. Symptoms of digital eye strain and dry eye went down, objective signs barely changed. Small study, no control group. doi:10.1016/j.clae.2022.101744
  • Kim et al., 2021, Contact Lens & Anterior Eye 44(3):101329. 41 people with dry eye did a short blinking exercise every 20 minutes for four weeks. Symptoms went down and incomplete blinks fell from 54% to 34%. No control group. https://pubmed.ncbi.nlm.nih.gov/32409236/
  • Wolffsohn et al., 2025, Contact Lens & Anterior Eye 48(5):102453. 15 repetitions three times a day for two weeks reduced symptoms and incomplete blinks. doi:10.1016/j.clae.2025.102453
  • Xu et al., 2025, npj Digital Medicine 8:703. Randomised trial of app-based blink training, 40 people, 30 days. Small study. https://www.nature.com/articles/s41746-025-02053-8
  • Singh et al., 2023, Cochrane Review CD013244.pub2. Blue-light filtering lenses may not reduce eye strain from screens: 17 randomised trials, 619 participants, low certainty. That is why we do not recommend them. doi:10.1002/14651858.CD013244.pub2

When to see a doctor

  • Symptoms persist even though you take breaks.
  • Double vision.
  • Eye pain or marked redness.
  • Sudden loss of vision, even brief: this is urgent.
  • After 40, reading up close has become hard: you probably need reading glasses, an ophthalmologist or optometrist can prescribe them.

Neck and shoulders

Why

At a screen, the upper trapezius holds the shoulders and head in one position for a long time. The load is small but continuous. The head often drifts forward toward the screen. This posture is associated with neck pain in adults, but it has not been shown to cause it. For office neck and shoulder pain, strength exercises for these muscles have the best evidence.

What the app does

  • Micro-breaks rotate through neck exercises: slow tilts and turns in a single plane. No neck circles.
  • Optional: a daily 2-minute neck and shoulder strength routine following the Andersen protocol (for example shrugs or lateral raises with an elastic band). Done regularly, the routine adds a couple of repetitions, up to four, and suggests holding an elastic band or a small bottle of water: in the Andersen trials the load grew as the muscles got used to it. It comes a couple of hours into your work day, and a night shift gets it a couple of hours into the shift.
  • A gentle “change posture” cue every 30 minutes.

What studies show

  • Chen et al., 2018, Physical Therapy 98(1):40-62. Systematic review of 27 randomised trials in office workers. Neck and shoulder strengthening reduced pain: SMD 0.59 (0.29 to 0.89), moderate quality. General fitness: 0.43. Workstation ergonomics: low quality evidence. https://pubmed.ncbi.nlm.nih.gov/29088401/
  • Andersen et al., 2008, Journal of Applied Physiology. 42 women with trapezius myalgia. Specific strength training cut pain by 42-49%, cycling did not. https://pubmed.ncbi.nlm.nih.gov/18948442/
  • Andersen et al., 2011, Pain 152(2):440-446. 198 working adults. 2 minutes a day, 5 days a week with an elastic band reduced neck and shoulder pain almost as much as 12 minutes. doi:10.1016/j.pain.2010.11.016
  • Andersen et al., 2011, Scandinavian Journal of Work, Environment & Health. Secondary analysis of the same trial: headache frequency fell by 43% (2 minutes a day) and 56% (12 minutes). https://pubmed.ncbi.nlm.nih.gov/21617837/
  • Mahmoud et al., 2019, Current Reviews in Musculoskeletal Medicine. Forward head posture is associated with neck pain in adults. Causality is not shown. https://pubmed.ncbi.nlm.nih.gov/31773477/
  • On neck circles. There is no direct evidence of harm. Physiotherapists usually advise single-plane movements and we follow that advice. This is practitioner opinion, not a study result.

When to see a doctor

  • Pain or numbness spreading into the arm.
  • Arm weakness.
  • Neck pain after an injury, fall or accident.
  • Neck pain with fever, dizziness, vision or speech problems: this is urgent.
  • Pain that wakes you at night.
  • Pain lasting longer than 6 weeks.

Back and long sitting

Why

Long uninterrupted sitting is harmful not because we “sit wrong” but because we move too little. Moving every half hour to hour helps muscles and metabolism: blood sugar rises less after meals. No posture has been found that protects against back pain. As physiotherapists put it, the best posture is the next posture: changing it is what helps.

What the app does

  • Every 45 minutes (30, 45 or 60, your choice) it suggests standing up for 3 minutes: back and leg exercises, a short walk, a glass of water.
  • A gentle “change posture” cue every 30 minutes.
  • Statistics show your time at the computer and your longest sitting stretch.

What studies show

  • Ekelund et al., 2016, The Lancet. Meta-analysis of more than 1 million people. 60-75 minutes a day of moderate activity eliminated the excess mortality linked to high sitting time. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(16)30370-1/abstract
  • Bull et al., 2020, British Journal of Sports Medicine: WHO guidelines. Adults: 150-300 minutes of moderate activity a week and less sedentary time. WHO does not name a specific break frequency. doi:10.1136/bjsports-2020-102955
  • Dunstan et al., 2012, Diabetes Care 35(5):976-983. 2 minutes of walking every 20 minutes after a meal: postprandial glucose down 24% (light walking) and 29.6% (moderate), insulin down 23%. doi:10.2337/dc11-1931
  • Duran, …, Diaz, 2023, Medicine & Science in Sports & Exercise 55(5):847-855. 11 participants. 5 minutes of walking every 30 minutes: glucose spikes down 58%, blood pressure down 4-5 mmHg, better mood. Small study. doi:10.1249/MSS.0000000000003109
  • Shrestha et al., 2018, Cochrane Review. Sit-stand desks cut sitting by 84-116 minutes a day. Low quality evidence, health effects unclear. doi:10.1002/14651858.CD010912.pub5
  • Swain et al., 2020, Journal of Biomechanics 102:109312. Systematic review: no consensus that spinal posture causes low back pain. doi:10.1016/j.jbiomech.2019.08.006
  • O’Sullivan et al., 2020, British Journal of Sports Medicine. “10 facts about back pain”: posture is not the cause, the best posture is the next posture. https://pubmed.ncbi.nlm.nih.gov/31892534/

When to see a doctor

Urgently, if back pain comes with:

  • numbness in the groin, buttocks or inner thighs (“saddle” area);
  • problems with bladder or bowel control;
  • leg weakness that is getting worse.

Also see a doctor if the pain started after an injury, if you have fever, unexplained weight loss, a history of cancer, severe night pain, or pain lasting longer than 4-6 weeks.

Hands

Why

Mouse and keyboard keep the hands and forearms in one position for hours, which can cause fatigue and discomfort in the forearms. A link between computer use and carpal tunnel syndrome has not been established: in studies, heavy computer users do not get it noticeably more often than other people, and the difference is within chance. So we do not claim the exercises protect against it. They are there to let the hands rest and change position.

What the app does

  • Some micro-breaks include simple hand and finger movements.
  • The breaks themselves come every 20 minutes: studies show this reduces forearm discomfort.

What studies show

When to see a doctor

  • Numbness or tingling in the thumb, index and middle fingers, especially at night.
  • Thumb weakness, dropping things.
  • Symptoms lasting longer than 2-4 weeks.
  • Pain after an injury.

Legs

Why

When we walk, the calf muscles contract and help push blood up the veins to the heart. When we sit, this pump is almost off. By evening the legs feel swollen and heavy. Very long sitting without breaks has been linked to blood clots, but in healthy young people this risk is low, and it has not been directly shown that office breaks prevent clots. Breaks do reduce swelling and heaviness.

What the app does

  • The stand-up break every 45 minutes suggests getting up, walking and doing leg exercises such as calf raises.
  • Statistics show your longest stretch without standing up.

What studies show

  • Healy et al., 2010, Journal of the Royal Society of Medicine 103:447. Case-control study: people who sat 10 or more hours a day and at least 2 hours without getting up had 2.8 times the odds of venous thromboembolism (95% CI 1.2 to 6.1). doi:10.1258/jrsm.2010.100155
  • Braithwaite et al., 2016, JRSM Open. A second, larger study by the same group, 200 cases and 200 controls. The same definition of long sitting was not significantly linked to clots (odds ratio 1.18), but each extra hour of average daily sitting raised the odds by about 8% (1.08). A weak association. https://pubmed.ncbi.nlm.nih.gov/27540486/
  • Peddie et al., 2021, PLOS ONE. Randomised crossover trial, 18 adults. 2-minute walks every 30 minutes increased blood flow in the popliteal artery by about 80% compared with sitting; standing still helped only briefly. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781669/

When to see a doctor

Call emergency services if:

  • one leg is swollen, painful, red or warm;
  • you suddenly feel short of breath or have chest pain.

If you have had blood clots, use hormonal contraception, are pregnant, are being treated for cancer or recently had surgery, talk to your doctor about how often you should get up and whether you need anything else.

Water

Why

When the body loses noticeably more water than it gets, attention drops, mood worsens and a headache may follow. At work, people often forget to drink. At the same time, “8 glasses a day” is not a scientific norm: we get water from food and from any drink, including tea and coffee.

What the app does

  • Every 90 minutes it shows a small “drink some water” card in the corner of the screen. No window opens.
  • The reminder can be turned off.

What studies show

When to see a doctor

  • Do not force yourself to drink beyond thirst: too much water in a short time is dangerous (blood sodium drops).
  • If you have heart or kidney failure and your doctor has limited your fluids, follow your doctor and turn the water reminder off in settings.
  • Constant strong thirst, frequent urination, dry mouth for no reason: a reason to have your blood sugar checked.

Breathing

Why

Slow breathing, around 6 breaths a minute, strengthens the vagal influence on the heart: heart rate variability goes up. Many people feel calmer after a few minutes of it.

What the app does

  • Optional breathing pause: breathe in for 4 seconds, out for 6 seconds, about 6 breaths a minute. No breath holds, no forced breathing.

What studies show

When to see a doctor

  • Dizziness or tingling in the fingers or lips: go back to normal breathing.
  • Breathing exercises do not treat anxiety disorders or panic attacks. If anxiety gets in the way of your life, see a doctor or therapist.
  • Shortness of breath, chest pain, choking attacks: see a doctor, urgently if it starts suddenly.

Workstation

Why

A good workstation does not make long sitting harmless, but it removes extra strain: no craning toward the screen, no bent wrists, no squinting at glare.

What the app does

  • The app does not check your workstation. The tips below are worth doing once.

Based on OSHA (US Occupational Safety and Health Administration) guidance:

  • Top of the screen at or slightly below eye level.
  • Screen at arm’s length, 50-100 cm.
  • Elbows at about 90–120°, wrists straight.
  • Feet flat on the floor or on a footrest.
  • Lower back supported by the backrest.
  • 2-3 fingers’ width between the seat edge and the back of the knee.
  • Lighting without glare on the screen.

What studies show

So setting up your workstation is worth it for comfort, but moving and taking breaks matter more.

When to see a doctor

If discomfort continues after adjusting your workstation and taking regular breaks, see the sections on eyes, neck, back and hands.

Micro-breaks in general

Why

During a short break both the muscles and attention get to rest.

What the app does

  • Short breaks every 20 minutes, longer ones every 45 minutes.
  • Does not interrupt calls: it only checks whether another program is using the camera or microphone and never opens them itself. Waits while you are in a fullscreen app, respects system Do Not Disturb where the system lets it be read.
  • Focus mode for 25 or 50 minutes, and work hours.

What studies show

  • Albulescu et al., 2022, PLOS ONE. Meta-analysis of micro-breaks: more vigour (d = 0.36), less fatigue (d = 0.35). Overall effect on performance not significant (d = 0.16). Longer breaks had bigger effects. https://pubmed.ncbi.nlm.nih.gov/36044424/
  • McLean et al., 2001 and Galinsky et al., 2000, 2007: see “Hands”.

When to see a doctor

Constant fatigue that does not go away after rest and weekends is a reason to see a GP.

End of the day

Why

If you manage to stop thinking about work after work, rest and sleep are better. A short end-of-day ritual helps you switch off.

What the app does

  • Optionally reminds you to finish work at the end of your working day.
  • Every evening (or once a week, if you choose) asks how much your eyes, neck, back and hands bothered you, from 0 to 3. Answers stay on your computer.
  • The “Result” page in the statistics sets your answers next to the breaks you did. It is self-observation, not proof of what helps: workload, sleep and holidays change how you feel too.

What studies show

  • Wendsche & Lohmann-Haislah, 2017, Frontiers in Psychology. Meta-analysis: detaching from work in free time is linked to better wellbeing and sleep and less burnout. These are correlations, not proof of cause. https://pubmed.ncbi.nlm.nih.gov/28133454/
  • Boubekri et al., 2014, Journal of Clinical Sleep Medicine. Pilot study, 49 people: those who worked near windows slept about 46 minutes longer. Weak data, but getting some daylight will not hurt. https://pubmed.ncbi.nlm.nih.gov/24932139/

When to see a doctor

If you have slept badly for more than three weeks or constantly lack energy or mood, see a doctor.

References

  1. Computers, Digital Devices, and Eye Strain. American Academy of Ophthalmology. American Academy of Ophthalmology (aao.org), 2024. Open the page · Are Blue Light-Blocking Glasses Worth It?
  2. Computer vision syndrome. American Optometric Association. American Optometric Association (aoa.org). Open the page
  3. Digital eye strain: prevalence, measurement and amelioration. Sheppard AL, Wolffsohn JS. BMJ Open Ophthalmology, 2018. DOI · PubMed · Free full text
  4. The effects of breaks on digital eye strain, dry eye and binocular vision: Testing the 20-20-20 rule. Talens-Estarelles C, Cerviño A, García-Lázaro S et al. Contact Lens & Anterior Eye, 2023. DOI · PubMed
  5. Therapeutic benefits of blinking exercises in dry eye disease. Kim AD, Muntz A, Lee J et al. Contact Lens & Anterior Eye, 2021. DOI · PubMed
  6. Optimisation of blinking exercises for dry eye disease. Wolffsohn JS, Travé-Huarte S, Bahra I et al. Contact Lens & Anterior Eye, 2025. DOI · PubMed
  7. A smartphone-based blink training application for alleviating dry eye signs and symptoms. Xu Z, Shen J, Jiang M et al. npj Digital Medicine, 2025. DOI · PubMed · Free full text
  8. Blue-light filtering spectacle lenses for visual performance, sleep, and macular health in adults. Singh S, Keller PR, Busija L et al. Cochrane Database of Systematic Reviews, 2023. DOI · PubMed · Free full text
  9. Workplace-Based Interventions for Neck Pain in Office Workers: Systematic Review and Meta-Analysis. Chen X, Coombes BK, Sjøgaard G et al. Physical Therapy, 2018. DOI · PubMed
  10. Effect of physical training on function of chronically painful muscles: a randomized controlled trial. Andersen LL, Andersen CH, Zebis MK et al. Journal of Applied Physiology, 2008. DOI · PubMed
  11. Effectiveness of small daily amounts of progressive resistance training for frequent neck/shoulder pain: randomised controlled trial. Andersen LL, Saervoll CA, Mortensen OS et al. Pain, 2011. DOI · PubMed
  12. Effect of brief daily exercise on headache among adults: secondary analysis of a randomized controlled trial. Andersen LL, Mortensen OS, Zebis MK et al. Scandinavian Journal of Work, Environment & Health, 2011. DOI · PubMed
  13. The Relationship Between Forward Head Posture and Neck Pain: a Systematic Review and Meta-Analysis. Mahmoud NF, Hassan KA, Abdelmajeed SF et al. Current Reviews in Musculoskeletal Medicine, 2019. DOI · PubMed · Free full text
  14. Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women. Ekelund U, Steene-Johannessen J, Brown WJ et al. The Lancet, 2016. DOI · PubMed
  15. World Health Organization 2020 guidelines on physical activity and sedentary behaviour. Bull FC, Al-Ansari SS, Biddle S et al. British Journal of Sports Medicine, 2020. DOI · PubMed · Free full text
  16. Breaking up prolonged sitting reduces postprandial glucose and insulin responses. Dunstan DW, Kingwell BA, Larsen R et al. Diabetes Care, 2012. DOI · PubMed · Free full text
  17. Breaking Up Prolonged Sitting to Improve Cardiometabolic Risk: Dose-Response Analysis of a Randomized Crossover Trial. Duran AT, Friel CP, Serafini MA et al. Medicine & Science in Sports & Exercise, 2023. DOI · PubMed
  18. Workplace interventions for reducing sitting at work. Shrestha N, Kukkonen-Harjula KT, Verbeek JH et al. Cochrane Database of Systematic Reviews, 2018. DOI · PubMed · Free full text
  19. No consensus on causality of spine postures or physical exposure and low back pain: A systematic review of systematic reviews. Swain CTV, Pan F, Owen PJ et al. Journal of Biomechanics, 2020. DOI · PubMed
  20. Back to basics: 10 facts every person should know about back pain. O'Sullivan PB, Caneiro JP, O'Sullivan K et al. British Journal of Sports Medicine, 2020. DOI · PubMed
  21. Carpal tunnel syndrome and the use of computer mouse and keyboard: a systematic review. Thomsen JF, Gerr F, Atroshi I. BMC Musculoskeletal Disorders, 2008. DOI · PubMed · Free full text
  22. Is carpal tunnel syndrome related to computer exposure at work? A review and meta-analysis. Mediouni Z, de Roquemaurel A, Dumontier C et al. Journal of Occupational and Environmental Medicine, 2014. DOI · PubMed
  23. Exercise and mobilisation interventions for carpal tunnel syndrome. Page MJ, O'Connor D, Pitt V et al. Cochrane Database of Systematic Reviews, 2012. DOI · PubMed · Free full text
  24. Efficacy of tendon and nerve gliding exercises for carpal tunnel syndrome: a systematic review of randomized controlled trials. Kim SD. Journal of Physical Therapy Science, 2015. DOI · PubMed · Free full text
  25. Computer terminal work and the benefit of microbreaks. McLean L, Tingley M, Scott RN et al. Applied Ergonomics, 2001. DOI · PubMed
  26. A field study of supplementary rest breaks for data-entry operators. Galinsky TL, Swanson NG, Sauter SL et al. Ergonomics, 2000. DOI · PubMed
  27. Supplementary breaks and stretching exercises for data entry operators: a follow-up field study. Galinsky T, Swanson N, Sauter S et al. American Journal of Industrial Medicine, 2007. DOI · PubMed
  28. Prolonged work- and computer-related seated immobility and risk of venous thromboembolism. Healy B, Levin E, Perrin K et al. Journal of the Royal Society of Medicine, 2010. DOI · PubMed · Free full text
  29. Venous thromboembolism risk associated with protracted work- and computer-related seated immobility: A case-control study. Braithwaite I, Healy B, Cameron L et al. JRSM Open, 2016. DOI · PubMed · Free full text
  30. The effects of prolonged sitting, prolonged standing, and activity breaks on vascular function, and postprandial glucose and insulin responses: A randomised crossover trial. Peddie MC, Kessell C, Bergen T et al. PLOS ONE, 2021. DOI · PubMed · Free full text
  31. Dehydration Impairs Cognitive Performance: A Meta-analysis. Wittbrodt MT, Millard-Stafford M. Medicine & Science in Sports & Exercise, 2018. DOI · PubMed
  32. Mild dehydration affects mood in healthy young women. Armstrong LE, Ganio MS, Casa DJ et al. The Journal of Nutrition, 2012. DOI · PubMed
  33. Mild dehydration impairs cognitive performance and mood of men. Ganio MS, Armstrong LE, Casa DJ et al. British Journal of Nutrition, 2011. DOI · PubMed
  34. Scientific Opinion on Dietary Reference Values for water. EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA). EFSA Journal, 2010. DOI
  35. "Drink at least eight glasses of water a day." Really? Is there scientific evidence for "8 x 8"?. Valtin H. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, 2002. DOI · PubMed · Dartmouth Medical School news release, 8 August 2002
  36. How Breath-Control Can Change Your Life: A Systematic Review on Psycho-Physiological Correlates of Slow Breathing. Zaccaro A, Piarulli A, Laurino M et al. Frontiers in Human Neuroscience, 2018. DOI · PubMed · Free full text
  37. Effects of voluntary slow breathing on heart rate and heart rate variability: A systematic review and a meta-analysis. Laborde S, Allen MS, Borges U et al. Neuroscience & Biobehavioral Reviews, 2022. DOI · PubMed
  38. Effect of breathwork on stress and mental health: A meta-analysis of randomised-controlled trials. Fincham GW, Strauss C, Montero-Marin J et al. Scientific Reports, 2023. DOI · PubMed · Free full text
  39. Brief structured respiration practices enhance mood and reduce physiological arousal. Balban MY, Neri E, Kogon MM et al. Cell Reports Medicine, 2023. DOI · PubMed · Free full text
  40. Computer Workstations eTool. Occupational Safety and Health Administration (OSHA). U.S. Department of Labor, OSHA (osha.gov). Open the page · Workstation Components: Monitors
  41. Ergonomic interventions for preventing work-related musculoskeletal disorders of the upper limb and neck among office workers. Hoe VC, Urquhart DM, Kelsall HL et al. Cochrane Database of Systematic Reviews, 2018. DOI · PubMed · Free full text
  42. "Give me a break!" A systematic review and meta-analysis on the efficacy of micro-breaks for increasing well-being and performance. Albulescu P, Macsinga I, Rusu A et al. PLOS ONE, 2022. DOI · PubMed · Free full text
  43. A Meta-Analysis on Antecedents and Outcomes of Detachment from Work. Wendsche J, Lohmann-Haislah A. Frontiers in Psychology, 2017. DOI · PubMed · Free full text
  44. Impact of windows and daylight exposure on overall health and sleep quality of office workers: a case-control pilot study. Boubekri M, Cheung IN, Reid KJ et al. Journal of Clinical Sleep Medicine, 2014. DOI · PubMed · Free full text

All sources with short summaries