NIOSH Training for Nurses on Shift Work and Long Work Hours

Nights Difficult

Why is night shift so difficult?

When you work the night shift, you fight three elements:

• You are working against your circadian clock, which is strongly influenced by the sun’s light-dark cycle.^1,2 The human body’s physiology drives sleeping at night in the dark and being awake during the daylight. The sun’s light-dark cycles also drive your body to sleep at night and be active during the daytime. This makes staying awake during night shift difficult. In addition, each cell in the body actually has its own internal clock. When you are awake at night, these cellular clocks do not adjust well, so your digestion, thermoregulation, and other functions are off-kilter.
• You might get less sleep and poorer-quality sleep than those working the day shift,^3,4 so you are more likely to be sleep deprived.
• Your personal relationships might become strained because your family and friends function on daytime schedules.