Sleeping poorly is linked with a higher risk of dying from heart disease and cancer, according to the American Heart Association.

Sleeping over eight hours might be too much sleep, while sleeping less than six hours can be too little sleep. New research suggests that people who exercise are more protected from heart disease and cancer, no matter how much they sleep.

The study found people who slept more than eight hours happened to be older women, obese and have health problems, and were less likely to exercise. People who slept less than six hours were younger, but also less likely to exercise.

The World Health Organization recommends 150 minutes a week of exercise, but says any movement is good for you.