Poor sleep is sometimes linked to an unhealthy diet, a Finnish study shows. People who sleep too little eat almost 40 grams less fruit and vegetables per day compared to people who sleep the normal seven to eight hours per night. Both sleeping less than seven hours per night and more than nine hours per night were associated with a low consumption of fruit and vegetables. Sleep, diet and physical activity form a unit and a positive change in one of these is reflected in a positive change in the other two, says the researcher behind the study. Last year, a Swedish study also showed that deep sleep becomes shallower in people who eat unhealthy food such as frozen pizza and ready-made meatballs compared to people who eat a healthier salmon stew. However, it is not known which substance or substances in the unhealthy diet resulted in a more shallow deep sleep. Previous research has shown that dark, leafy green vegetables such as spinach and kale are good sources of magnesium, which can help support sleep.