. 2021 Nov 22;13(11):4178. doi: 10.3390/nu13114178

Table 1.

Population, design, shift work definition(s) and exposure, and main outcomes of the reviewed studies ¹.

Ref.	Loc.	N.	Sex	Occupation	Design	Type of Shift Work	Exposure and Definition(s) of Shifts	Main Outcomes
Ref.	Loc.	N.	Sex	Occupation	Design	Type of Shift Work	Exposure and Definition(s) of Shifts	MetS	BMI	Gluc.	CVD	BP	Lip.	Nut.
[10]	USA	14	Both	n.s.	Lab study	Simulated	Exposure: No shiftwork in the year prior to the study Simulated night shift: 16 h of wakefulness, 8 h of sleep opportunity		x					x
[11,12]	USA	14	Both	n.s.	Lab study, crossover	Simulated	Exposure: No shift work in the past 3 years and <6 months cumulative lifetime exposure to shift work Simulated night shift: Kept awake from 19:00 to 11:00, 8 h sleep opportunity from 11:00 to 19:00			x	x	x	x
[13,14]	USA	9	Both	n.s.	Lab study, crossover	Simulated	Exposure: ≥12 months of consecutive shift work with ≥5 night shifts per month prior to the study Simulated night shift: Kept awake from 19:00 to 11:00, 8 h sleep opportunity from 11:00 to 19:00			x	x	x
[15]	USA	12	Both	Healthcare	Lab study, crossover	Simulated	Exposure: Rotating shifts of 3 consecutive day and nights shifts (07:00–19:00 and 19:00–07:00, resp.), with a minimum of 3 night shifts per month for ≥1 year Simulated day and night shift following the same clock times			x
[16]	AUS	17	Both	n.s.	Lab study	Simulated	Exposure: No shift work in the past 2 months Simulated day shift: Kept awake from 07:00 to 22:00, 9 h sleep opportunity from 22:00 to 07:00 Simulated night shift: Kept awake from 17:00 to 08:00, 9 h sleep opportunity from 08:00 to 17:00			x
[17]	AUS	16	Both	n.s.	Lab study, crossover	Simulated	Exposure: No shift work prior to the study Simulated night shift: Kept awake from 20:00 to 08:00							x
[18]	AUS	22	Both	Private companies	Randomized crossover trial ²	Night shift work	Exposure: ≥12 consecutive months of nights (permanent, rotating, or split night shifts) prior to the study		x					x
[19]	USA	14	Both	Healthcare	Cross-sectional, prospective	Day, night, and rotating shift work	Exposure groups: Day, night, and rotating shift workers	x	x	x		x		x
[20,21]	USA	24	Fem.	Healthcare	Cross-sectional, prospective	Day and night shift work, without rotating shift work	Exposure groups: Day shift workers (from 07:00–08:00 to 15:00–20:00) vs. night shift workers (from 19:00–23:00 to 07:00); each shift lasting 8 h or 12 h		x			x		x
[22]	CAN	73	Fem.	Healthcare	Cross-sectional, secondary analysis ³	Evening and night shift work, including irregular or rotating schedules	Exposure groups: Shift workers (any work outside of daytime hours) vs. non-shift workers		x			x		x
[23]	KOR	9989	Fem.	Healthcare	Cross-sectional, prospective ⁴	n.s.	Exposure groups: Current shift workers vs. day workers		x					x
[24]	POL	522	Fem.	Healthcare	Cross-sectional, prospective ⁵	Rotating shift work	Exposure groups: Rotating night shift workers (2–7 night shifts per month, usually between 19:00 and 07:00) vs. day workers		x	x				x
[25]	CHE	65	Male	Private and public institutions	Cross-sectional, prospective ⁶	Rotating shift work	Exposure: Mixed shift schedules during at least 6 months with work between 20:00 and 06:00		x	x				x
[26]	GBR	20	Fem.	Healthcare	Cross-sectional, secondary analysis	Rotating shift work	Exposure: Day shifts and ≥2 consecutive night shifts of ≥8 h duration between 20:00 and 08:00							x
[27]	AUS	63	Both	Mixed	Cross-sectional, prospective	Night and rotating shift work	n.s.							x
[28]	BEL	1529	Male	Private and public institutions	Cohort, prospective	Rotating shift work	Exposure groups: Two or three rotating shifts vs. day workers	x	x	x		x	x
[29]	USA	54,724	Fem.	Healthcare	Cohort, prospective ⁷	Day/evenings only, nights only, early mornings only, rotating with nights, or rotating with no nights	Exposure groups: Day/evenings only, nights only, early mornings only, rotating shifts with nights, rotating shifts with no nights, others/no work - Day shift: Work between 7:00 and 15:00 - Evening shift: Work between 15:00 and 23:00 - Night shift: Work between 23:00 and 07:00 - Early morning: Work between 4:00 and 9:00		x	x	x	x	x	x
[30,31]	USA	177,184; 143,410	Fem.	Healthcare	Cohort, prospective ^7,8	Rotating shift work	Exposure: At least 3 night shifts per month in addition to day and evening shifts in that month		x	x		x	x	x
[32]	DNK	19,873	Fem.	Healthcare	Cohort, prospective ⁹	Night, evening, or rotating shift work	n.s.		x	x	x	x		x
[33]	CHN	3871	Both	Private companies	Cohort, prospective ¹⁰	Night shift work: permanent, rotating, or irregular work	Exposure groups: Permanent, rotating, or irregular night shift workers, day shift workers Night shift workers: At least one night between 24:00 and 06:00 per month over 1 year, with subgroups: - Permanent night shift work: Only during nighttime - Rotating shift work: Fixed pattern of daytime and nighttime shifts (e.g., morning, evening, then night shifts, and repeated cycle) - Irregular shift work: No fixed schedule of nights Daytime workers: All not meeting the criteria above		x					x
[34]	NOR	2965	Both	Healthcare	Cohort, prospective ¹¹	Day, evening, night, and rotating shift work	Exposure groups: Day shifts only, evening shifts only, two-shift schedule (day + evening), or three-shift schedule (day + evening + night) - Day shift: Work between 07:00 and 15:00 - Evening shift: Work between 14:30 and 22:00 - Night shift: Work between 22:00 and 07:00		x
[35,36]	NLD	485; 596	Both	Healthcare	Cohort, prospective ^12,13	Day, evening, night, and rotating shift work	Exposure groups: Day, evening, night, and rotating shift workers Day workers: Only between 08:00 and 17:00, including those who stopped rotating and night shifts ≥ 6 months prior to study in Loef et al. [36] Rotating shift workers: Rotating between day shifts (mostly 07:30–16:00), evening shifts (mostly 15:00–23:00), and night shifts (mostly 23:00–07:30)		x				x	x
[37]	NLD	1061	Both	Healthcare	Cohort, prospective ¹⁴	Day, evening, night, and rotating shift work	Exposure groups: Day, evening, night or rotating shifts ≥1 year before each wave of the cohort - Evening shift: Work ending before 24:00 - Night shift: Work continuing or starting after 24:00 - Day workers: No past or current shift work		x			x	x
[38]	Intl	n.a.	Both	Mixed	Systematic review and meta-analysis ¹⁵	Night shift work	Night shift: Work between 24:00 and 05:00	x	x	x		x	x
[39]	Intl	n.a.	Both	Mixed	Systematic review and meta-analysis¹⁵	Rotating shift work and other types of shift work (mixed)	Any work outside of daytime hours	x
[40]	Intl	n.a.	Both	Mixed	Systematic review and meta-analysis ¹⁵	n.s.	n.s.	x
[41]	Intl	n.a.	Both	Mixed	Systematic review and meta-analysis ¹⁵	Night shift work	Night shift: Work between 24:00 and 05:00		x
[42]	Intl	n.a.	Both	Mixed	Systematic review and meta-analysis ¹⁵	n.s.	Any work outside of daytime hours (from 09:00 to 17:00)		x
[43]	Intl	n.a.	Both	Healthcare	Systematic review and meta-analysis ¹⁵	n.s.	Any work outside of daytime hours		x
[44]	Intl	n.a.	Both	Mixed	Systematic review and meta-analysis ¹⁵	n.s.	n.s.			x
[45]	Intl	n.a.	Both	Mixed	Systematic review and meta-analysis ¹⁵	Night, rotating and uncategorized shift work	Night shift: Mixed schedule of day and night work Rotating shift: Non-fixed shift work			x
[46]	Intl	n.a.	Both	Mixed	Systematic review and meta-analysis ¹⁵	Rotating shift work and other types of shift work (mixed)	Permanent night shift or rotating shift, or work arrangements differing from daytime hours (from 07:00–08:00 to 17:00–18:00)				x
[47]	Intl	n.a.	Both	Mixed	Systematic review and meta-analysis ¹⁵	Night and rotating shift work	n.s.					x
[48]	Intl	n.a.	Both	Mixed	Systematic review and meta-analysis ¹⁵	Permanent night shift work or rotating shift work	Rotating shift: 2 shifts of 12 h each, or 3 shifts of 8 h each						x
[49]	Intl	n.a.	Both	Mixed	Systematic review and meta-analysis ¹⁵	Night shift work	Night shift: Work including the hour of midnight and ending before 08:00							x
[50]	Intl	n.a.	Both	Mixed	Systematic review and meta-analysis ¹⁵	Day, evening, night, and rotating shift work	Night shift: Work after 18:00, not lasting >12 h							x
[51]	Intl	n.a.	Both	Mixed	Systematic review	Night and rotating shift work	n.s.							x
[52]	Intl	n.a.	Both	Mixed	Systematic review	Rotating shift work and other types of shift work (mixed)	Any work outside of daytime hours							x

Abbreviations: BMI, Body mass index; BP, Blood Pressure; CVD, Cardiovascular disease; Fem, Female; Gluc, Glucose metabolism; Intl, International (multiple countries); Lip, Lipid profile; Loc, Location (3-letter country code); MetS, Metabolic syndrome; N., Number of participants (for individual studies); n.a., not applicable; n.s., not specified; Nut, Nutrition/eating patterns; Ref, Reference(s). ¹ See accompanying text in Section 3 and Section 4 for details on the reviewed studies focusing on shift work. ² Study results adjusted for sex, age, BMI, and occupation. ³ Study results adjusted for age. ⁴ Study results adjusted for age, BMI, breakfast skipping, physical activity, alcohol consumption, smoking status, marital status, family income, education, sleep, self-reported health status. ⁵ Study results adjusted for age, waist to hip ratio, height, gastro-intestinal diseases, diabetes, concomitant medication, smoking, season, number of children, job duration, chronotype. ⁶ Study results adjusted for total energy intake, the workplace. ⁷ Study results adjusted for age, ethnicity, BMI, metabolic factors (waist circumference, diastolic BP and HDL cholesterol), family history of diabetes, menopausal status, total energy intake, dietary score, physical activity, alcohol consumption, smoking status, concomitant drugs. ⁸ Study results adjusted for age, ethnicity, BMI, family history of diabetes, menopausal status, total energy intake, dietary score, physical activity, alcohol consumption, smoking status, concomitant drugs, marital status, health status. ⁹ Study results adjusted for age, BMI, acute myocardial infarction, hypertension, intake of fatty meat, fruit and vegetables, physical activity, alcohol consumption, smoking status, marital status, employment status. ¹⁰ Study results adjusted for sex, age, intake of fruit and vegetable, physical activity, alcohol consumption, smoking status, marital status, education, working hours, sleep, mental stress. ¹¹ Study results adjusted for sex, age, BMI, marital status, children living at home, education. ¹² Study results adjusted for sex, age, physical activity, smoking status, marital status, education, occupation, working hours. ¹³ Study results adjusted for sex, age, alcohol consumption, smoking status, education, occupation, self-reported health status. ¹⁴ Study results adjusted for sex, age, concomitant medication, education, chronotype. ¹⁵ The meta-analyses listed above included source studies that adjusted for different confounding factors, but also some studies with no adjustment. We refer the reader to the original articles for further details.