.
The authors had earlier presented the findings at the National Cancer Research
Institute Conference (NCRI) in Glasgow.
, believed to be caused by a disruption in sleep
patterns, exposure to the
bright
environment, and other lifestyle factors. However,
The
study team set out to determine whether certain sleep traits could influence
breast cancer risk.
- The study employed a technique
Mendelian randomization, and analyzed genetic variants associated with
three specific sleep traits namely morning or evening chronotype (when a
person is most active), duration of sleep, and insomnia.
- An association noted during a
Mendelian randomization study increases the chances of a causal
relationship and reduces the scope for erroneous
conclusions caused by confounding factors.
Analyzing
Risk of Breast Cancer in Larks Vs Owls
- The trial
analyzed data from about 400,000 women who had provided their genetic
information either in the UK Biobank or the Breast Cancer Association
Consortium (BCAC) study.
- The study team
looked at 450 genetic markers related to sleep, including "chronotype"
(when a person is most active), sleep duration, and insomnia
- Using Mendelian
randomization method, the team were able to study breast cancer risk
independent of confounding factors such as smoking and alcohol
- The findings of the analysis found
that morning preference was associated with a slightly lesser risk of
breast cancer (one less woman per 100) than evening preference, which
translates to a 48-50% lower risk in morning larks
- Analysis of BCAC also found that
women who slept longer than the advised seven to eight hours per night had
a higher risk of developing breast
cancer by 20% for every additional hour. However,
analysis of UK Biobank data
revealed that there was little evidence for a link with both sleep
duration and insomnia
Dr. Rebecca Richmond, lead scientist from the
University of Bristol,
"The findings of a protective effect of morning preference
on breast cancer risk in our study are consistent with previous research
highlighting a role for night shift work and exposure to
"light-at-night" as risk factors for breast cancer." Potential
Merits & Demerits
- According to the authors, possible
demerits include that the study relied partly on self-reported sleep measures and comprised only
women of European ancestry, and so the
findings may not apply to other races
- The merits are that the scientists
used several methods to
analyze information from two highly respected resources,
and accounted for other possible and established risk factors. The results
were also the same after additional sensitivity analyses
Scope of the Study
- Further studies will be necessary to
unearth potential reasons between disruption in sleep behavior and breast
cancer risk since other factors like work and
family influence our sleeping and waking time, and the authors feel
this mismatch may account for some additional risk
- Although cancer
risk may be set in the genes, changing
our sleep behavior can help modify the risk
- The findings of the study suggesting
that matching our biological clocks to our occupational clocks may help
reduce disease risk
In summary, morning persons have a lower
risk of breast cancer in comparison to late risers and these findings suggest
that changing sleep behavior can improve health and reduce the risk
of cancer or other chronic diseases.
References : - Investigating Causal Relations Between Sleep Traits and Risk of Breast Cancer in Women: Mendelian Randomisation Study - (https://doi.org/10.1136/bmj.l2327)
Source: Medindia
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