Protocol
Daytime-only eating during night shift work
Two laboratory trials found that keeping meals out of the night during simulated night shifts prevented the worsening of glucose tolerance that night eating caused (Chellappa et al., Sci Adv, 2021; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 34860550; Centofanti et al., Diabetologia, 2025; PMID 39422718).
Grade C: human trials exist, but they are small, mixed or not yet repeated. This is not a finding that it does not work. How to read a grade →
At a glance
This page is about not eating during a night shift. In two lab studies, healthy people who were not shift workers stayed up at night as if on a night shift. Those who ate at night handled sugar worse afterward. Those who ate only during the day did not. In one small study of real night shift workers, skipping food from 1 a.m. to 6 a.m. for four weeks did not change blood sugar after a meal. No study has looked at diabetes or heart disease.
- What was measured
- How well the body handled a glucose drink before and after several simulated night shifts, by what and when people ate at night.
- How big
- After four simulated night shifts, glucose under the curve rose by 2.00 with a meal at night and by 0.96 with a snack at night, against 0.34 with fasting at night, a change too small to tell apart from chance.Read from the summary of PMID 39422718.
- Who it applies to
- Healthy young adults who were not shift workers, over a few simulated night shifts in a laboratory. A 4-week trial in real night shift workers found no change.
- Safety
- This record lists no specific safety warning.
- Compared with
- A meal or a snack eaten during the simulated night shift.
- Certainty
- Grade C, resting on: Two small laboratory trials in people who were not shift workers, and one null pilot trial in night shift workers.
- What would change this grade
- Could rise to B with: Randomized controlled trial People are assigned to the treatment or a comparison by chance, so the groups differ only in what they received. It is the design that can show cause and effect. of keeping food out of the night shift against usual eating, with calories matched. Who: Night shift workers with overweight or prediabetes, at least 100 per arm. Measured: HbA1c A blood test that reflects average blood sugar over the previous two to three months. and fasting glucose, with weight and blood pressure. Length: At least 6 months.
- Cost
- No price recorded yet.
- Sources
- 5 studies cited on this record, listed under Sources.
Two laboratory trials found that keeping meals out of the night during simulated night shifts prevented the worsening of glucose tolerance that night eating caused (Chellappa et al., Sci Adv, 2021; PMID 34860550; Centofanti et al., Diabetologia, 2025; PMID 39422718). A 4-week crossover A trial design in which each participant receives both the treatment and the comparison, one after the other, and serves as their own control. trial in 19 real night shift workers who fasted from 1 a.m. to 6 a.m. found no change in blood sugar or fat after meals (Leung et al., Nutr Metab Cardiovasc Dis, 2021; PMID 33994064).
Why this letter
Why this gradeGrade C, small or unreplicated trials. The reasoning, and what the grade does not cover.
Grade C on glucose tolerance during night work. Two independent laboratory trials of simulated night shifts found that moving meals out of the night prevented the loss of glucose tolerance that night eating caused (PMIDs 34860550, 39422718), but both enrolled healthy young adults who were not shift workers and ran for days. The one trial in real night shift workers, a 19-person pilot of an overnight fast, found no change in blood sugar or triglycerides after a test meal (PMID 33994064).
WHY NOT Bglucose tolerance after a test drink is not an established stand-in for a clinical outcome, the laboratory trials were short and small, and the only trial in shift workers was null.
WHAT THIS GRADE DOES NOT COVERa fixed eating window outside shift work, which has its own record under time-restricted eating; diabetes or heart disease outcomes, which no trial of meal timing in shift workers has measured; and mood and heart rhythm findings, which come from secondary analyses of one trial.
A grade describes the human evidence for a named use. It is not advice, and it is not a judgment on any individual prescription. How the letters are decided →
Who responds: this record's trial reading reports no subgroup that identifies who responds.
Evidence notes: randomized trial, not independently replicated The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away., mixed
Endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score. graded: Glucose tolerance after a glucose drink or test meal during night shift work, with meals kept out of the night (surrogate)
Last reviewed: November 2026
The trial that would change this grade.
A positive trial of this shape, supported by further trials, would move this entry to B.
Why the current trials fall short
The laboratory trials lasted days and enrolled people who were not shift workers. A trial of real night shift workers over months, measured on HbA1c, would test whether the laboratory finding carries over.
Why people believe itOne human source; no published case reports of benefit; no reports of harm.
The case for daytime-only eating is that the body handles sugar worse at night, so food eaten on a night shift arrives when the body is least ready for it.
What supporters point to, and what each source actually shows. None of it is enough to move this letter higher; the trial described above under Evidence wanted is what would.
- Human trial, blood or body markerIn a laboratory study of simulated night work, eating at night pulled the body's glucose rhythm out of step with its central clock, and eating only during the day kept them aligned. PMID 34860550
A case report describes what happened to one or a few patients. It cannot show the treatment caused the change, and reports of success are published more often than reports of failure.
A PubMed search in November 2026 found no published case report of benefit for this use.
Searched PubMed, November 2026: 1 case report record(s) returned. The one record is a journal commentary on meal timing and blood clotting tests; it does not describe meal timing during night work.
ClinicalTrials.gov, the public registry run by the U.S. National Library of Medicine, lists studies that are recruiting volunteers. The link below searches it for Chrononutrition among studies recruiting now. EBL has no relationship with any listed study and receives no payment for this link.
Search recruiting studies of Chrononutrition on ClinicalTrials.gov
Dose, form and timing
Fasting glucose and HbA1c at the usual interval set with a clinician; no target for meal timing is established.
As studiedDose, form, population and duration for every use.
A grade describes the intervention that was tested. Where the product on the shelf differs from it, this says so.
Safety
No safety data. Each caution on this record, sorted by what it rests on.
None recorded.
None recorded.
None recorded.
None recorded.
No safety data: EBL has found no trial or report of harm for this record. That is an absence of evidence, not a finding of safety.
Grade history
How this letter has changedLatest: No. 421 · November 2026 · First graded.
Keeping meals out of the night shift now has a record. In a laboratory trial of four simulated night shifts, glucose tolerance worsened with a meal or snack at night and not with fasting (Centofanti et al., Diabetologia, 2025; PMID 39422718). A pilot trial in 19 night shift workers found no change in blood sugar after meals (Leung et al., Nutr Metab Cardiovasc Dis, 2021; PMID 33994064). Grade C.PMID 39422718 PMID 33994064
Every change to a letter on this site is dated and published. The full evidence log →
Sources
- Citations
- Every paper cited on this page is matched to its PubMed record on every build.
- Retractions
- None of these papers is retracted or under a journal expression of concern. PubMed is checked again on every build.
- Read against the papers
- November 2026. By a language model (AI-assisted reading), not yet reviewed by a clinician.
- Outside review
- Not yet done. No reviewer outside EBL has checked this record.
What each of these checks can and cannot show: evidence integrity.
The evidence, in fullFive papers, each linked to its PubMed record.
Chellappa et al. (Sci Adv, 2021; PMID 34860550): 14-day laboratory protocol of simulated night work in healthy adults who were not shift workers, randomized to eating at night and during the day or eating during the day only; night eating impaired glucose tolerance and daytime-only eating prevented it. Chellappa et al. (Nat Commun, 2025; PMID 40199860): secondary analysis of the same trial, which randomized 20 participants; daytime-only eating prevented the fall in heart rate variability and the rise in the clotting factor PAI-1 seen with night eating. Qian et al. (Proc Natl Acad Sci U S A, 2022; PMID 36095195): secondary analysis of the same trial; depression-like and anxiety-like mood scores rose with night eating and not with daytime-only eating. Centofanti et al. (Diabetologia, 2025; PMID 39422718): open-label Everyone in the trial knows which treatment they are receiving, so expectations can shape the results, especially for symptoms people report themselves. cluster randomized trial in 55 healthy adults who were not shift workers, comparing a meal, a snack or fasting at night over four simulated night shifts; glucose tolerance worsened with the meal and the snack at night and not with fasting. Leung et al. (Nutr Metab Cardiovasc Dis, 2021; PMID 33994064): pilot randomized crossover trial in 19 night shift workers with abdominal obesity; a 4-week overnight fast from 1 a.m. to 6 a.m. did not change blood sugar or triglycerides after a test meal, and adherence was 95 percent.
How EBL searched for the trials (1 search)
The search that was run, what it returned, and what was left out and why, so the absence of evidence can be checked as well as its presence.
("shift work"[tiab] OR "shift workers"[tiab] OR "night shift"[tiab] OR "night work"[tiab] OR firefighters[tiab] OR nurses[tiab]) AND ("meal timing"[tiab] OR "time-restricted"[tiab] OR "daytime eating"[tiab] OR "night eating"[tiab] OR "eating window"[tiab] OR fasting[tiab]) AND (randomized controlled trial[pt] OR clinical trial[pt])PubMed watch: does a new study change the grade? (nothing new)
No new paper matching the search behind this grade has been added to PubMed since November 2026.
Last run November 2026. A letter on EBL moves only after a logged review. A new paper never moves a letter by arriving: it is read, the answer is written here, and any change to the letter is published in the evidence log.
Disclosure
Educational use only · Not medical advice · EBL grades published human evidence and does not recommend treatment. Stopping a prescription is a decision for your physician.
Evidence Based Longevity, Inc. is owner-operated and edited by Arnold Sandlow, D.C., a California-licensed chiropractor. Evidence Based Longevity publishes in English only · Machine translations are not produced or reviewed by EBL for accuracy
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