Findings of a recent animal study published in the journal Current Biology have lent weight to concerns regarding the ill effects of shift work on our health.

According to researchers, women with family history of breast cancer should stay away from working in shifts. However, they have also cautioned that for confirming that there’s a link between shift work and breast cancer further tests will have to be conducted on people.

The data presented in the report indicated that the mice gained 20% more weight in spite of consuming food in similar quantity.

We have seen previous studies on humans suggesting that the risk of diseases like breast cancer is higher in flight attendants and shift workers.


One of the most common arguments we hear is that disruption of the body clock or the internal rhythm of our body makes us more vulnerable to diseases. However, the link is vague as people who need to work in shifts might also have higher risk of having cancer due to other factors such as the amount of vitamin D they consume, their social class and their activity levels.

During the study, the body clock of mice with risk of having breast cancer was delayed by 12 hours every week. This continued for a year,

Without any disruption in sleep, the animals developed tumors after 50 weeks. However, after experiencing disturbance in their sleeping pattern on a regular basis, the mice got tumors eight weeks in advance.

The author of the study have written that this is the first time ever in recorded history a study is unequivocally showing association between breast cancer development and chronic light-dark inversions.

Interpreting these consequences for humans is right now difficult; however, researchers have guesstimated that under similar circumstances humans might become 10 kg heavier and women at risk of getting cancer might develop the disease five years in advance.

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Gijsbertus van der Horst, a member of the research team, said that if there’s any family that is at risk of developing breast cancer, he would advise the members of that family to not opt for shift work or become a flight attendant. Horst is a representative of Netherlands’ Erasmus University Medical Center.

The basic message the findings of this study send out for general public is that shift work, especially rotational shift work, is something very stressful and thus has consequences.