Night eating syndrome, characterized by a lack of appetite during the day and insomnia and increased appetite at night, may be caused by an abnormal response to stress.

Night eaters have a different pattern of hormonal release to stress than normal eaters.

Investigators studied stress hormone secretion patterns in five female night eaters and a comparison group of five women without the syndrome. The night eaters all consumed more than half of their daily food intake after 8 PM, and woke at least once during the night to eat.

The researchers injected the women with 100 micrograms of corticotropin-releasing hormone, which is released in response to stress and triggers the secretion of other stress hormones.

In general, the night eaters exhibited a gradual and slight increase in their stress hormones after the injection, followed by a gradual decrease, while their peers in the comparison group exhibited a rapid and significantly greater increase in their stress hormones, followed by a gradual decrease.

The night eaters' hormone secretion in response to induced stress was significantly weaker than their peers'.

The study group was worn out. For example, their levels of the stress hormone cortisol at the beginning of the study were higher than those seen in the comparison group. If you are stressed 24 hours a day, there will be no reaction when stress is induced.

In general, these findings indicate that the relationship between the adrenal gland which releases cortisol, the hypothalamus, where the appetite center is and the pituitary, where a lot of hormones are produced, is out of control. No wonder they night eaters eat late at night and wake up during the night."

American Journal of Physiology-Endocrinology and Metabolism February 2002;282:E366-E369