It’s a rarity to find Harborview nurse Angela Curtis working during the day. She prefers the night shift.

“It is quieter, it seems quieter at night,” she said.

But all that quiet could come with a price.

“We were one of the first to find that there is relationship between working nights and increased risk of breast cancer,” said Scott Davis, PhD, at Seattle’s Fred Hutchinson Cancer Research Center.

Now Fred Hutchinson cancer researchers are looking for reasons. The theory is it has to do with hormone levels. When you disrupt sleep, or are exposed to light during the night, it reduces your ability to produce the hormone melatonin. This in turn might be causing women like Angela to produce more estrogen than her counterparts, who work days.

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Circulating estrogen tends to increase the risk of developing breast cancers, doctors have found.

“We know from a number of studies that have been done over many years that increased circulating estrogen tends to increase the risk of developing breast cancers,” Davis said.  

Researchers will be tracking female shift workers in the health care field to find out if that theory holds up.

“Once you understand what's going on in terms of night shifts and disease risk, then you're obviously in a better position to perhaps devise some measures that will reduce that risk,” Angela said.”Maybe vitamins, maybe just changing your sleep patterns, just doing something different."

That's why Angela joined the study, to help find out if there's something she can do to lower her risk. Because at the end of the day, she’d much rather be starting work than finishing.

“I really like the night shift because there's actually less people around and it’s more calm. And you get to see the sunset and the sunrise outside,” she said.

The study is looking for women in the health care field ages 20 to 48 working nights and not on the pill or other hormonal forms of birth control.

For more information, call (206) 667-5704 or click on the link above.