Health Hazards of Shift Work

Dr. Alok VajpayeeProfessor & Head

Department of Occupational Health

All India Institute of Hygiene & Public Health

110, C.R. Avenue, Kolkata - 700 073

What is Shift Work ?

• Shift work is work scheduled, either permanently or frequently outside normal daytime working hours. e.g. – – Permanent work at night – Permanent work during

evening – Work hours with changing

assignment patterns.

Why shift work ?

• To maintain continuity of process by a series of teams.

Why continuity ? • Continuous nature of the technical process

involved (nuclear reactors, steel production, oil refineries etc.)

• Public service (Hospitals, communication etc.)• Purely economic reason – to make maximum use

of the industrial plant.

Some Major Early Morning Accidents (1)

• Nuclear power plant incidents at – Three Mile Island 1979.

• The Chernobyl nuclear disaster

• The Titanic ………..

• Many major train accidents.

Some Major Early Morning Accidents (2)

• The Union Carbide chemical accident in Bhopal.

• This is a time of great vulnerability

• Even those with high motivation to stay awake may succumb.

Accidents (3)

• Accidents rate decreases while the seriousness of accident increases during night.

Safety at Nuclear Establishments

• Indian Nuclear Reactors and Power Plants have an excellent record of maintaining highest level of safety and vigilance.

• We can not afford to compromise with alertness and vigilance.

• In case a disaster – – Generations will suffer – It will be severe blow to our nuclear

programme.

Circadian Rhythm (1)

• Humans are biologically day-oriented as a species.

• Function best during the

daylight hours

• Sleep best at night

Circadian Rhythm (2)

There is a built in body clock which controls : -

• Body temperature • Alertness • Muscle strength • Digestion • Hormone secretion • Blood pressure • Immediate & long term memory • Kidney function etc.

Body Temperature (1)

• Temperature is an indicator of overall metabolic rate. Body temperature and alertness are also correlated.

• In a typical dayshift cycle body temperature begins to rise just before wakeup time.

• Temperature rises according to daily function. Peaking approximately at 9 pm.

Body Temperature (2)

• As we sleep body temperature goes down.

• At early morning (around 4 – 5 am) temperature is minimum.

Desynchronization (1)

• If we work in the night shift but our body rhythm is in day mode, there is desynchronization. When we sleep in day after night work : - – Body temperature is increasing. – Digestive enzyme secretion is increasing. – Body metabolism is increasing. – Sleep is very difficult even if we are tired.

Desymnchronization (2)

• Leads to : - – Fatigue – Poor concentration – Impaired digestion – Difficult sleep

External Cues

• External time cues keep us in synchronization with the world.

Internal Body Clock (1)

• Experiments on volunteers living in complete isolation and darkness (without any time cues) revealed - – Our internal clock runs on 25 hour

cycle. – Our usual sleep / wake cycle with

time cues is synchronized with the 24 hour day – night cycle.

Internal Body Clock (2)

• It means our internal Body Clock is adjustable.

• We can make a clockwise adjustment at the rate of one hour per day.

• To shift an 8 hour clockwise shift in schedule, it takes about one week (with cues).

Hazards of Night Shift

• Biological

• Physiological

• Social

Biological Hazards (1)

• Sleep deprivation.

• Gastric and digestive disorders.

• Vague symptoms – malaise, irritability, fatigue, muscular pain, not feeling normal.

• Increases in cardio – vascular diseases.

• Poor pregnancy outcome.

Biological Hazards (2)

• Shift Work Mal-adaption Syndrome

5 – 20% of shift workers have marked difficulties in adopting to shift work.

The health problems in them are pronounced and they do not improve with time, instead get worse.

• High drop out.

Biological Hazards (3)

Conditions that may be exacerbated by shift work - – Sleep disorders – Asthma – Diabetes mellitus – Coronary Artery Disease – Individuals taking long term drug therapy.

Biological Hazards (4)

Conditions that may be exacerbated by shift work.

• Psychiatric disorders

• Gastrointestinal disorders

• Shift mal-adaption syndrome

Impact on Family & Social Life (1)

• Cut off from the community • Can not effectively participate in social life • Can not fulfill collective responsibilities • All family members can not get together

and organize family life• Neighbourhood relations and group

entertainment suffer

Impact on Family & Social Life (2)

• Drug and alcohol abuse are higher among shift workers

• Divorce and souse abuse rates are also higher

Performance (1)

• Psychomoter performance is significantly affected

• For persons with diurnal orientation, jobs done less efficiently during night –– Jobs involving vigilance, manual dexterity,

boring repetitive tasks, long term memory and fast reaction time.

Performance (2)

• Short term memory may improve during night

• Jobs performed best at night are those involving complex high cognition

Advantages of Night Shift

• Less supervision, more independence at night

• Less politics• Able to attend day classes • If nigh-shift allowance is given, increase in

income. • More useable daylight hours

Prevention and Control Strategies

1. What a night – shift employee can do for himself ?

2. What management can do for night shift employees ?

Strategy No. 1 Develop Night Life Style (1)

• Theoretically, continuous night-shifts are better because you can adapt your body rhythms to a regular schedule

• In 7 – 8 days circadian rhythm is totally inverted.

• Maintain this schedule consistently on days off too.

Develop Night Life Style (2)

• Reverting to a “normal” daytime schedule may harm you.

• Practically because of social and family responsibilities maintaining continuous night life style is never possible.

• Man is a social animal.

Anchor Sleep (2)

• On work days – sleep 8 am to 4 pm

• On days off – delay your sleep (sleep form 4 am to noon).

• The anchor period overlaps 4 common hours with your night shift times.

• Better than totally flip flopping between days and nights.

Compromise Solution Split – Sleep (1)

• If your shift schedule rotates at short interval, your body can not adapt quickly to sudden changes in biorhythms.

• The goal of split – sleep is to prevent body rhythms from shifting.

• When not working nights, sleep midnight to 8 am

• When working night shifts, split your sleep into 2 portions 8 am to noon and 6 pm to 9 pm.

Advantages of Split - Sleep

• Two sleep periods help to cancel the “Shift – effect” each has on body rhythms.

• You are sleeping close to end and beginning times of your usual sleep time. This maintains some consistency with cues.

• Some find sleeping right before shift, helps them stay alert and awake.

Compromise SolutionCompletion Sleep (1)

Compromise SolutionCompletion Sleep / Siesta Sleep

• For those with 4 pm to 12 (mid-night) schedule may get up at 6 – 7 am to send the kids to school and after a short gap they may sleep again to complete their sleep.

• After taking lunch, we become sleepy. Night shift employees may use post lunch period to complete their sleep. It will keep you alert and makes up for lost hours of sleep.

The Sleep Environment

• Warm bath prior to bed. • Sleep in a dark, quiet, cool and comfortable

room. • DO NOT DISTURB ME.• Maintain a sleep schedule. Your family

members and friends must know your sleep schedule.

• Develop a pre – bed time ritual – read newspaper, listen to soft music etc. This allows you to unwind from your shift.

NUTRITION TIPS (1)

• Shift workers are move susceptible to digestive problems. They develop irregular eating habits. They eat junk foods.

• At night, digestive system is at rest. • Eating at night means eating when your digestive

system is at rest. • Carbohydrates are easily digested in comparison to

fat and protein. • Eat more of carbohydrate rich food at night. Avoid

excessive fat and protein rich food at night.

NUTRITION TIPS (2)

• Bring easily digestible food from home.• Take small amount at a time. Heavier meals

are more difficult to digest. • Avoid too much caffeine late in your shift.

It can make it hard for you to fall asleep after you come back home.

• Try to eat one meal with family daily.

NUTRITION TIPS (3)

• Establish a meal schedule (normal for you)

• Eat at least 3 meals spaced at consistent intervals to fuel your body.

How to Remain Awake

• Hot drinks tea or coffee. Caffeine is a stimulant.

• If scheduled short naps are allowed during the shift. A short nap of 15 – 20 minutes may increase your level of alertness.

• Move around. Mild exercise during work. • Wash face with cold water.

Safety

• Alertness and concentration are lowest at very early morning hours 3 – 6 am.

• Be aware of this fact. Work very carefully and deliberately.

• Double check everything. Double check verbal orders from your sleepy supervisors also.

Family and Social Life

• Family support is very important for shift work to be successful.

• Discuss your schedule with family. Arrive at ground rules for sleep, meals etc.

• Make phone calls to your home.

• Plan time with friends, relatives and family.

Commute Home Safely

• While going back home – if possible do not drive yourself. Take a company car or public transport.

• If you are driving yourself, drive defensively.

• Your family is waiting for you at home.

Time to consider a change

• The ability to shift work is different in every person.

• In spite of your best efforts to adjust, you may not succeed. Your health may suffer. Family and social life may shatter. You may suffer psychologically.

• It may be the time to consider changing your job.

Thank You