- The human body has a 24-hour clock.
- This clock controls sleep, hormones and repair.
- Scientists studied mice that had cancer.
- Some mice had a normal light cycle.
- Other mice had a disturbed light cycle.
- Disturbed light made tumors grow faster and earlier.
- Tumors were more likely to spread to lungs.
- The immune system became weaker and less active.
- Healthy breast tissue became more vulnerable to cancer.
- Researchers want to help people who work at night.
Difficult words
- hormone — chemical in body that changes how cells acthormones
- repair — process of fixing or healing body parts
- tumor — a mass of abnormal cells in the bodytumors
- immune system — body system that fights infections and disease
- disturb — to make something not normal or regulardisturbed
- vulnerable — easy to harm or get disease
Tip: hover, focus or tap highlighted words in the article to see quick definitions while you read or listen.
Discussion questions
- Do you sleep at the same time every day?
- Do you sleep with a light on or off?
- Have you ever worked at night?
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