Researchers say a lack of sleep changes our genes, which means it affects our bodies and can even make us ill.
The team at the University of Surrey tested the blood of people who had different amounts of sleep.
The study showed that more than 700 genes changed when people had slept only 6 hours a night for a week.
This is important because the genes are all linked to protein which helps rebuild tissue in the body.
Researchers say this shows not enough sleep could make it difficult for your body to mend.
Tips for getting a good night's sleep
- Go to bed at the same time each night even on weekends. This helps your body clock get used to these times.
- Sleep in a comfortable bed.
- Create a calm bedroom environment. Sleep in a dark room and avoid turning your bedroom into an entertainment centre with televisions, computers and stereos.
- Regular exercise is a great way to improve your sleep. Just be careful not to do it close too bed time as exercise produces stimulants that stop the brain from relaxing quickly.
- A healthy diet will also help but eating a large heavy meal too close to bedtime will interfere with your sleep.