Night work
Each hour of night work imposes a greater workload than
the same hour during a day shift (3 am versus 3 pm),
because of the effects of circadian rhythms. Work which is
physically or mentally demanding, monotonous or requires
high vigilance can lead to fatigue which will be worsened
by night work.
Night work combined with extended hours is extremely
hazardous in terms of sleep debt and fatigue, and may
result in an increased risk of accidents at work.
Disrupted eating patterns
The timing of meals is important from both physiological
and social perspectives. Shift work, particularly night work,
can continually disrupt eating patterns.
Digestive function is governed by circadian rhythms and is
reduced at night. Eating large meals, or intake of coffee
and other drinks containing caffeine to stay awake at night,
can result in a range of symptoms such as indigestion,
abdominal pains and bowel disturbances.
Studies show that shift workers are more likely to display
these symptoms than day workers. In the medium to long
term, more serious diseases of the gastrointestinal tract
may develop.
Stress
Almost 14% of respondents to the 1997 ACTU nationalsurvey on stress at work named long hours and rostering
among the three most stressful conditions in their
workplace. This was highest in the construction, mining
and transport areas. Almost 12% reported difficulties
organising childcare.
Stress associated with shift work and extended hours may
be caused by any, or a combination, of:
• poor roster design (including the predictability of
hours)
• the physical and mental demands of the work
• the ability to balance childcare, family and other
responsibilities
• the physiological and psychological effects of
disrupted circadian rhythms.