The research behind what we make
Shift Focus is built on evidence, not hype — so here's the evidence, including the parts that are still being worked out. Below are the peer-reviewed studies behind our ingredients and the claims we make about Shift Work, with a plain note on what each one looked at.
How to read this: these are studies of ingredients and of Shift Work physiology — not studies of our finished products, and study doses often differ from our serve sizes. We've noted that where it matters. Our products are food-based supplements, not medicines, and aren't intended to diagnose, treat, cure or prevent any disease. Where the evidence is mixed, we say so.
Creatine Monohydrate
Best known as a sports supplement, creatine also has a growing evidence base for cognitive performance — including during sleep loss, which is why it's in a product built for Shift Workers.
Gordji-Nejad A, Matusch A, Kleedörfer S, et al. Single dose creatine improves cognitive performance and induces changes in cerebral high energy phosphates during sleep deprivation.
Scientific Reports. 2024;14:4937.
What it measured: Randomised, double-blind, placebo-controlled crossover trial (15 adults). A single high dose of creatine (0.35 g/kg — roughly 25 g for an 80 kg person) during 21 hours of sleep deprivation reduced fatigue and improved memory and reasoning-task performance and processing speed versus placebo, from about 3.5 hours after dosing. Note the study dose is far higher than a standard 5 g serve.
doi.org/10.1038/s41598-024-54249-9Gordji-Nejad A, Matusch A, Hengstler L, et al. Single-dose creatine reduces sleep deprivation-induced deterioration in cognitive performance.
Nutrients. 2026;18(8):1192.
What it measured: Follow-up trial (29 adults) using a lower single dose (0.2 g/kg) during sleep deprivation, reporting a mitigating effect on decline in logical, numerical and language-processing tasks and on psychomotor vigilance. Still above a 5 g serve, but closer to it.
doi.org/10.3390/nu18081192Prokopidis K, Giannos P, Triantafyllidis KK, et al. Effects of creatine supplementation on memory in healthy individuals: a systematic review and meta-analysis of randomized controlled trials.
Nutrition Reviews. 2023;81(4):416–427.
What it measured: Pooled analysis of randomised trials of creatine and memory in healthy people, finding a measurable benefit to memory, more pronounced in older adults. The broader evidence base behind general cognitive-support claims.
PMID 35984306What this evidence does and doesn't show
The sleep-deprivation trials used single doses well above a standard 5 g serve, and were small. They point to a genuine, well-documented effect of creatine on cognition under fatigue — but they don't establish that 5 g reproduces that acute result. We include them because they're the most relevant research to Shift Work, not because they test our exact serve.
Hydrolysed Collagen Peptides
Collagen is the 'repair' side of Fuel & Repair. Collagen peptides supply glycine, proline and hydroxyproline — amino acids that make up the body's connective tissue, with proposed roles across joint, skin, bone and muscle health. The evidence is promising in places and genuinely unsettled in others, so here's the honest picture rather than only the flattering half.
Khatri M, Naughton RJ, Clifford T, Harper LD, Corr L. The effects of collagen peptide supplementation on body composition, collagen synthesis, and recovery from joint injury and exercise: a systematic review.
Amino Acids. 2021;53(10):1493–1506.
What it measured: A systematic review reporting strong evidence that 5–15 g/day collagen peptides improve joint pain and function, and a modest but significant improvement in muscle recovery. The authors note 13 of 15 included studies were commercially funded, raising the possibility of publication bias — so we flag that alongside the positive finding.
PMID 34491424Kuwaba K, Kusubata M, Taga Y, et al. Dietary collagen peptides alleviate exercise-induced muscle soreness in healthy middle-aged males: a randomized double-blinded crossover clinical trial.
Journal of the International Society of Sports Nutrition. 2023;20(1):2206392.
What it measured: Randomised, double-blind crossover trial reporting reduced post-exercise muscle soreness with collagen peptides. Conducted via a research organisation contracted to a collagen manufacturer.
PMID 37133292Genç AS, Yılmaz AK, Anıl B, et al. Effect of supplementation with type 1 and type 3 collagen peptide and type 2 hydrolyzed collagen on osteoarthritis-related pain, quality of life, and physical function: a double-blind, randomized, placebo-controlled study.
Joint Diseases and Related Surgery. 2025. PMID 39719905.
What it measured: Randomised, placebo-controlled trial (31 osteoarthritis patients) reporting improvements in pain and quality-of-life measures over 8 weeks, with no significant difference on some functional tests. Note: a clinical osteoarthritis population, not healthy Shift Workers — relevant to the joint-comfort role, not a direct read-across to recovery.
PMID 39719905Bischof K, Stafilidis S, Bundschuh L, et al. Influence of specific collagen peptides and 12-week concurrent training on recovery-related biomechanical characteristics following exercise-induced muscle damage — a randomized controlled trial.
Frontiers in Nutrition. 2023;10:1266056.
What it measured: 55 participants took 15 g collagen peptides or placebo alongside training for 12 weeks; some improvement in recovery-related measures after exercise-induced muscle damage. Study dose (15 g) differs from our serve.
PMID 38035363The honest counter-evidence
A leading independent lab (van Loon's group) has published two findings that cut against an over-confident collagen story, and we'd rather show them than hide them.
Holwerda & van Loon (2022), Nutrition Reviews 80(6):1497–1514 (PMID 34605901): a narrative review concluding that while collagen peptides are theoretically well-suited to support connective tissue, there is currently no human data confirming they actually increase connective-tissue protein synthesis. Promising mechanism, unproven in humans.
Aussieker et al. (2023), Med Sci Sports Exerc 55(10):1792–1802 (PMID 37202878): found collagen protein ingestion did not increase muscle connective-tissue protein synthesis after exercise. Important caveat — this tested collagen protein, a larger molecule, not the hydrolysed peptides we use — but the outcome it measured is exactly the mechanism collagen claims often lean on, so it belongs here.
Why hydrolysed peptides — and the limit of that argument
Our product uses hydrolysed collagen peptides, not intact collagen protein. Hydrolysis breaks collagen into low-molecular-weight peptides that are more readily digested and absorbed, reaching the bloodstream as intact bioactive di- and tripeptides (Virgilio et al., 2024, Frontiers in Nutrition 11:1416643, PMID 39149544). That's why peptide-specific trials — not whole-protein studies — are the relevant evidence for a product like ours.
But we won't overstate it: better absorption shows the peptides get in. It does not by itself prove a larger downstream effect on recovery or tissue synthesis — that link is still being established, as Virgilio's own authors note. Absorbed is not the same as proven to work. That's the honest state of it, and it's why our copy says collagen 'may' support recovery.
Shift Work, Sleep & Cognition
The claims we make about what Shift Work does to sleep, alertness and the body's clock are drawn from the following research.
Boivin DB, Boudreau P, Kosmadopoulos A. Disturbance of the circadian system in shift work and its health impact.
Journal of Biological Rhythms. 2022;37(1):3–28.
What it measured: A review of how shift work disrupts the circadian system and the downstream effects on sleep, alertness and long-term health. The circadian system resists adapting from a day- to night-oriented schedule, shown by a lack of substantial phase shifts in melatonin and cortisol.
PMID 34969316Chellappa SL, Morris CJ, Scheer FAJL. Effects of circadian misalignment on cognition in chronic shift workers.
Scientific Reports. 2019;9:699.
What it measured: A controlled crossover study (Harvard Medical School) finding circadian misalignment worsens sustained attention, information processing and visual-motor performance in chronic shift workers, especially after 11+ hours awake. It also reports that under 3% of permanent night workers fully adapt their melatonin rhythm. A small study (7 participants) — confirmatory, not definitive.
PMID 30679522Folkard S. Do permanent night workers show circadian adjustment? A review based on the endogenous melatonin rhythm.
Chronobiology International. 2008;25(2):215–224.
What it measured: The foundational review establishing that few permanent night workers fully adapt their body clock to night shifts. Older, but still the reference point current research builds on (it's the source the 2019 Chellappa study cites for this finding).
PMID 18533325Leso V, Fontana L, Caturano A, Vetrani I, Fedele M, Iavicoli I. Impact of shift work and long working hours on worker cognitive functions: current evidence and future research needs.
International Journal of Environmental Research and Public Health. 2021;18(12):6540.
What it measured: A review of the evidence linking shift work and long working hours to effects on cognitive function.
PMID 34204504Kazemi R, Haidarimoghadam R, Motamedzadeh M, et al. Effects of shift work on cognitive performance, sleep quality, and sleepiness among petrochemical control room operators.
Journal of Circadian Rhythms. 2016;14:1.
What it measured: A field study of shift workers linking shift schedules to measurable effects on cognitive performance, sleep quality and sleepiness.
PMID 27103934Shakhloul M, Amer A, Zekry M, et al. Effective interventions for reducing the negative effects of night shifts on doctors' and nurses' health and well-being: a systematic review.
Cureus. 2025;17(5):e83385.
What it measured: A 2025 systematic review of interventions to reduce the negative effects of night shifts on the health and well-being of doctors and nurses.
PMID 40458350Melatonin & Night-Shift Health
Referenced in our blog content on sleep, recovery and night-shift physiology.
Zanif U, Lai AS, Parks J, et al. Melatonin supplementation and oxidative DNA damage repair capacity among night shift workers: a randomised placebo-controlled trial.
Occupational and Environmental Medicine. 2025;82(1):1–6.
What it measured: A randomised placebo-controlled trial examining melatonin supplementation and oxidative DNA damage repair capacity in night shift workers.
PMID 39993913Lavado-Fernández E, Pérez-Montes C, Robles-García M, Santos-Ledo A, García-Macia M. Melatonin at the crossroads of oxidative stress, immunity, and cancer therapy.
Antioxidants. 2026;15(1):64.
What it measured: A review of melatonin's roles in oxidative stress, immune function and cancer biology.
Antioxidants 15(1):64Pacheco D, Singh A. Treatments for shift work disorder.
Sleep Foundation (consumer resource). 2025.
What it measured: A consumer-facing guide on managing shift work disorder, including light therapy and light avoidance. A reputable secondary source, not primary research.
sleepfoundation.orgSleep Health Foundation (Australia). Shift work.
Sleep Health Foundation fact sheet.
What it measured: Australian public-health guidance on sleep loss and impairment associated with shift work. Source for our figures on sleep after night shifts and fatigue-related impairment.
sleephealthfoundation.org.auFurther Reading
Accessible books and guides we rate — useful background reading rather than primary research.
- Walker, M. (2017). Why We Sleep: The New Science of Sleep and Dreams. Scribner (US) / Allen Lane (UK). ISBN 978-1-5011-4431-8.
- Walch, O. (2025). Sleep Groove: Why Your Body's Clock Is So Messed Up and What To Do About It. Andrews McMeel Publishing. ISBN 978-1-5248-9295-1. (Walch is a University of Michigan neurology researcher.)
- Dunican, I. C., & Smithies, T. D. (2024). A Guide for Sleep Health and Shiftwork: Practical Strategies for Individuals and Organisations. Melius Consulting. ISBN 978-1-7636-5644-4.
This page is provided for transparency about the research behind our ingredients and advice. It is general in nature and is not medical advice. Individual results vary. Our products are food-based supplements and are not intended to diagnose, treat, cure or prevent any disease. If you have a health condition, are pregnant or breastfeeding, or take medication, talk to your doctor or pharmacist before starting any supplement. Always read the label and use only as directed.