All that Halloween candy can cause a sugar crash that resembles a hangover: brain fog, irritability, headache and fatigue.

What’s happening is that refined sugars increase your endorphins and make you feel good. However, your body knows that high blood sugar levels are dangerous, so it sends out insulin which causes blood sugars to rapidly drop leading to feelings of crankiness, irritability, fatigue and weakness.

Regularly consuming excess sugar can take a toll on health over time. Not only does excess sugar contribute to weight gain and increase your risk of diabetes and heart disease, but also excess sugar can actually change your brain. Sugar elevates dopamine levels ― the pleasure part of the brain ― which boosts mood, motivation, and attention, and helps regulate movement, learning, and emotional responses. When dopamine from external sources regularly floods into the system, over time, the brain eventually makes less of its own dopamine. When the sugar source is cut off, cravings kick in.

Cravings may be more intense for some people than others. A small study published in the International Journal of Obesity in 2014 took brain scans of children while they ate sugar. The study showed that the brains of obese children lit up more than the brains of kids of average weight, indicating that they showed an enhanced response to, and a greater psychological reward from, sugar. Additionally, access to sugar can lead to behavior and neurochemical changes that resemble the effects of a substance of abuse.

To avoid the health and mood effects of sugar, limit your intake of food with added sugars, such as sugary drinks, candy, cookies and desserts.