Shift Work and

Long Work Hours

By : Dr. Ar. SafaeianOccupational medicine

specialist

Shift work

Shift work involves work at times other than daytime hours of approximately 7:00 A.M. to 6:00 P.M.

Almost 15% of full-time workers (or 15 million Americans) work on evening, night, rotating, split, or employer-arranged irregular shifts

Social needs and economic factors promote the use of shift work and long hours.

Critical services with shift work

1. police

2. fire protection

3. health care

4. transportation

5. communications

6. public utilities

7. military service

8. industries require continuous processing

Shift Work Schedules

What is the best or worst work schedule?

☻There is no simple answer to this question because there is no ideal schedule that fits every situation.

☻Both good and bad points can be found in most work schedules.

Types of Work Schedules

Different schedules might be used by the same occupation, the same industry, or even the same workplace.

5 days on a single shift followed by 2 days off (max).

Depending on the job, it is even possible to work 7, 10, or 14 days in a row.

☻Offshore oil rig workers, might work 2 weeks out on the rig followed by 2 weeks off at home.

Time of Shift

24 hour operations usually are divided into 2 or 3 shifts. Start- and end-times depend on the length of the shift.

☻Day shift (also called morning or first shift) starts around 5 to 8 a.m. and ends around 2 to 6 p.m.

☻Evening shift (also called afternoon or second shift) starts around 2 to 6 p.m. and ends around 10 p.m. to 2 a.m.

☻Night shift (also called third, “graveyard,” or “mid” shift) starts around 10 p.m. to 2 a.m. and ends around 5 to 8 a.m.

2nd-shift worker efficiency levels are typically 3–5% below 1st shift

3rd shift 4–6% below 2nd shift

The productivity level, i.e. cost per employee, is often 25% to 40% lower on 2nd and 3rd shifts due to fixed costs which are "paid" by the first shift.

Permanent versus Rotating Schedules:

Permanent :

☻Most permanent night workers never really get used to the schedule.

Fatigue occurs because most night workers go back to a day schedule on their days off.

They sleep less during the day, so they don’t recover from fatigue.

Over several days, fatigue can accumulate to unsafe levels.

Rotating :

☻Often used because they are considered fairer to all workers

☻ they can never completely adapt to a set work schedule.

Speed and Direction of Rotation:

Speed :

●the number of consecutive day, evening, or night shifts before a shift change occurs.

Direction :

●Forward rotation, from day to evening to night shift.

●Backward rotation, from day to night to evening shift.

SPEED OF ROTATION

Longer rotations (3-4weeks of working the same hours) allow workers more time to get used to night shifts. However, workers usually return to a day schedule on their days off.

A fast rotation (every 2 days) allows no time to get used to night work.

☻Some researchers prefer the fast rotation, because the worker quickly pass the hard shifts and then has a couple of days off.

☻Very fast rotations are used in Europe more than in America.

DIRECTION OF ROTATION

Can affect the ability of circadian rhythms to adapt to the change in work times.

Forward rotation is better for helping a worker adjust to new sleep times(because it is easier to go to bed later and wake up later than earlier).

Backward rotations work against the body rhythm by forcing the worker to go to sleep earlier and earlier.

backward rotation schedules are used frequently in US.

Work-Rest Ratios

The more a person works, the less time he or she will have for rest.

How many breaks during the shift and the length of breaks ?

-Several short breaks might be better than a few long breaks.

How many days works in a row

How Regular or Predictable?

Most jobs have a very regular, set schedule. HCW, breakdown at a factory, Railroad

workers It is difficult to get adequate rest. Maybe they are on call and never get deep,

satisfying sleep because they are always listening for the phone. Some people call this “sleeping with one eye open.”

Table 1: Work Schedule FeaturesExample Particulars Feature

Day, evening or night

Time of Shift

Shift Rotation

Fixed shift times (no rotation)

Permanent

Changing shift times Rotating

Rapid: 2 days per shift Number of workdays before shift change

speed

Slow: 21 days per shift

Clockwise: day to evening to night

Clockwise (forward) or counterclockwise (backward) change

direction

Counter: day to night to evening

Example Particulars Feature

Work-Rest Ratios

5 workdays/2 rest days

7 workdays/3 rest days

Number of workdays to number of rest days Overtime workdays

Weekly

8 h work/16 h rest12 h work/12 h restLunch, coffee break

Work hours to rest hoursRest breaks within a dayOvertime work hours

Daily

Example Particulars Feature

How Regular or Predictable?

Emergency or “on-call”part of the schedule Unplanned overtimeDemand-based schedulingor working off a “call board”

Can affect any otherpart of the schedule

Shift work

The relationship between shift work and health and safety is influenced by :

work schedule the job the worker the work environment others (ergonomic ,organizational factors, job

demands, workers' personalities, sociodemographic characteristics, geographic location, recreational resources, housing arrangements, sociometric patterns, and social support)

Risks Associated with Shift Work

Sleep, Sleepiness Circadian Rhythms, Performance, and Safety Social and Familial Disruptions Long-term Effects and Vulnerable Groups

Sleep, Sleepiness

The most direct effect of shift work is the reduction in the length and quality of sleep

Night-shift workers have lighter, more fragmented, and less restful daytime sleep

Rotating shift workers obtain less sleep, than permanent schedules.

No adaptation

Circadian rhythms refer to biologic rhythms that show a cyclic rise and fall about once a day.

Circadian Rhythms, Performance, and Safety

The timing of the circadian rhythms are slow to change and generally take several days to readjust after abrupt

Disturbances in circadian rhythms lead to reductions in the length and quality of sleep, increase negative, GI symptoms

Injury risk increased :18% during afternoon/evening shift and 34% during the night

Social and Familial Disruptions

Shift workers often work in the evening and sleep during the day

The disruptions depend on: worker's schedule, family, gender of the worker, presence of children, the degree of flexibility in the worker's social contacts and leisure pursuits.

Long-term Effects

32% of night workers and 26% of rotating shift workers experience long-term insomnia and excessive sleepiness and are unable to adapt their sleep adequately on these shifts.

Vulnerable Groups

Unstable angina or MI

HTN requiring regular medications

IDDM Asthma requiring

regular medication Psychiatric illnesses

requiring regular medication

Alcohol or drug abuse

GI diseases Sleep disorders Epilepsy requiring

medication within the past year

Renal impairment Thyroid and

suprarenal pathologies

Malignant tumors Pregnancy

Long-term Effects

Aging is associated with less tolerance of shift work

The sleep changes may begin as early as the 30s and 40s, so some workers who initially adapted well to shift work during their younger years may show more symptoms as they grow older

Long Work Hours

Working a minimum of 50 hours per week

Estimated that over 26% of U.S. men and 11% of U.S. women worked long hours in 2000.

Risks Associated with Long Work Hours

The overtime work is associated with small but significant increases in adverse physical and psychological outcomes like:

poorer perceived general health increased injury rates more illnesses increased mortality

Countermeasures

Efforts to promote adaptation to or ease the difficulties of coping with shift work and long work hours include

strategies for employers strategies for workers

Countermeasures Work schedules /rest breaks during work Sleep strategies Altering circadian rhythms (bright or blue light) Optimally timing physical activity Improving physical conditioning Pharmacologic aids or using caffeine Dietary regimens Stress reduction techniques Social support groups Providing family counseling.