By Charnicia E. Huggins
NEW YORK (Reuters Health) – 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, new study findings show.
"Night eaters have a different pattern of hormonal release to stress than normal eaters," lead study author Dr. Grethe S. Birketvedt of the University of Tromso in Norway told Reuters Health.
To investigate, Dr. Birketvedt and her colleagues studied stress hormone secretion patterns in five female night eaters and a control 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 challenged the subjects with 100 micrograms of corticotropin-releasing hormone, which is normally 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 investigators report in the February edition of the American Journal of Physiology-Endocrinology and Metabolism. Thus, the night eaters' hormone secretion in response to induced stress was significantly weaker than their peers'.
The study group was "worn out," Dr. Birketvedt explained. For example, their levels of the stress hormone cortisol at the beginning of the study were higher than those seen in the controls. "If [you are] stressed 24 hours a day, there will be no reaction when stress is induced," Dr. Birketvedt said.
In general, these findings indicate that the relationship between the adrenal gland, hypothalamus, and pituitary is out of control, Dr. Birketvedt continued. However, "with these findings, we can find a treatment that turns the biological clock back to normal."