1 . It happens from time to time that after a whole morning of studying, you are tired in the afternoon. It is then that you may want to eat something sweet, perhaps a sweet drink or a chocolate bar to lift your mood.     1    

But a study suggests that sugar can make you feel worse rather than lift your mood. The German and UK researchers collected data from 31 studies involving nearly 1,300 adults.     2     Those emotions include anger, alertness, depression and tiredness. They found that people who have too much sugar become more tired and less alert within an hour, and that these feelings become more intense over time.

According to researchers, when people take in sugar, their blood sugar levels rise rapidly, leading to a burst of energy and a short “feel good” period. However, as they begin to digest the sugar, their blood sugar levels decrease quickly, leading to a bad feeling.     3     As with caffeine, this prevents the body from relaxing, leaving people being tired and less alert.

    4     According to WHO, it is healthy to have the sugars found naturally in fruit, vegetables and milk, so long as they make up less than 5 percent of our daily total energy intake.

So the next time you feel tired and can’t concentrate on study and work, perhaps you should think twice before you bite into a chocolate bar. There are still other ways to relieve tiredness.     5