Ten Years of Blood and Shift Work: What the Data Tell Us About Metabolism, Sleep, and the Body’s Clock

R.E. Hengsterman
Oct 1
3 min read

Updated: 1 day ago

Shift work doesn’t just change when you sleep. It changes the blood itself. Over a decade, the numbers add up—fasting glucose creeping higher, triglycerides edging up, thyroid function slipping out of rhythm. It’s not just fatigue you feel after a string of nights; it’s a slow recalibration of the body’s metabolic machinery.

A new 10-year retrospective cohort study (2013–2022) in a metal manufacturing plant followed 204 rotating shift workers and compared them with 204 day workers. Every lab value, every blood draw, every physical across a decade was pulled together. The result? A clear metabolic fingerprint of what shift work does.

The snapshot: What shift work changed

Compared with day workers, shift workers carried significantly higher levels of:

BMI – weight creeping upward over the decade.
Fasting blood sugar (FBS) – stronger odds of impaired glucose metabolism.
Triglycerides (TG) – a consistent elevation over 10 years.
Liver enzymes (SGPT/SGOT) – markers of strain and early liver dysfunction.
Thyroid-stimulating hormone (TSH) – a subtle but real drift toward thyroid imbalance.
Platelet counts (PLT) – another marker tied to inflammation and vascular risk.
Systolic blood pressure (SBP) – slightly higher, though not always statistically dramatic.

Meanwhile, day workers—matched for job type and environmental exposures—showed more stable numbers. They slept longer, moved more, and reported better sleep quality.

Why this matters for shift workers

The numbers tell a story: it’s not just one variable, it’s a cluster. Blood sugar, lipids, liver enzymes, and thyroid hormones all shifted in the same direction under the pressure of disrupted circadian rhythms, shorter sleep, and reduced physical activity.

The regression analysis showed the strongest effects of shift work on:

Fasting glucose (+0.49)
Triglycerides (+0.33)
Liver enzyme SGPT (+0.29)
TSH (thyroid balance) (+0.29)
Physical activity and BMI (+0.20, +0.18)
Sleep duration and quality (+0.14, +0.11)

These are the building blocks of metabolic syndrome—and the seeds of long-term cardiovascular and endocrine disease.

What’s behind it

Circadian disruption: The body’s natural rhythm for insulin release, fat metabolism, and thyroid regulation is anchored to light/dark cycles. Shift work scrambles those anchors.
Behavioral patterns: Shift workers reported less physical activity, shorter sleep duration, and poorer sleep quality. Add fast-food reliance and sugar-heavy diets, and the biology accelerates.
Silent accumulation: None of these changes happen overnight. But across ten years, the “normal” lab slip becomes disease risk.

The paradox: survival now vs. survival later

Shift work is here to stay—nearly 20% of the global workforce is on shifts, and in places like Singapore it’s closer to one in three. The paradox is this: the same work that sustains families and economies quietly rewires biology in ways that shorten healthspan.

This isn’t a reason to quit—it’s a reason to intervene earlier.

Practical interventions that make a difference

The study didn’t prescribe solutions, but the implications are clear:

Metabolic screening should be routine for long-term shift workers: HbA1c, lipids, thyroid, liver enzymes—not just a blood pressure cuff once a year.
Physical activity programs (like the 17-minute HIIT intervention in Norway) can stabilize glucose and blood pressure, even in rotating shifts.
Workplace support: Healthier food options, controlled lighting, and scheduled physical breaks are more than perks—they’re protective factors.
Sleep interventions: Targeting sleep quality (dark rooms, cooling, routine, melatonin timing) matters as much as the hours you manage to get.

The Shift Worker’s Paradox take-home

Ten years in the blood don’t lie. Compared with day workers, shift workers were more likely to carry higher glucose, triglycerides, liver stress markers, and thyroid disruption—silent shifts that accumulate toward chronic disease.

The work isn’t going away. But the biology is negotiable—if we start treating metabolic health as part of the job, not just a side effect of it.

Source: Soltanzadeh, A., Eyvazlou, M., Mohammad-ghasemi, M. et al. Investigating the relationship between shift work schedule and blood and metabolic parameters: a 10-years retrospective cohort study. Sci Rep 14, 17297 (2024). https://doi.org/10.1038/s41598-024-68378-8