Whenever you wake up feeling hungry or cannot sleep without a midnight snack, you can blame your body for periodically releasing the hormone orexin, according to a recent study.
The study was done by researchers at UT Southwestern Medical Center at Dallas who had been investigating how the hormone controls sleep and hunger, when they discovered its connection to the protein HIF-1.
"Orexins are peptide hormones that regulate sleep-wake cycles, appetite and metabolism," said Devanjan Sikder, lead author of the study. "Orexin basically keeps you awake. During the sleep phase, its level drops."
The study was published Thursday in the online version of Genes and Development.
"Our findings suggest that sleep and metabolism are intimately linked," Sikder said. "When sugar level drops to a critical level, orexin starts building up urging you to wake up and find food. It has long been known that we are more active when we are hungry and energy reserves are low. Remember, it is virtually impossible to sleep on an empty stomach. We show that orexin ensures that energy is efficiently harvested to keep you vigilant so that you can fetch food."
The researchers used gene screening to discover which genes orexin activated or inhibited. In the study, when orexin was used to stimulate a component of HIF-1 called HIF1-alpha, the expression of a variety of genes that burned sugar to provide energy for the body were increased.
This research helps link orexin to the metabolic system because when blood sugar is low, the body increases its production of the hormone. When the body gets hungry, the increase in orexin activates HIF-1 production, which increases the body's metabolism, according to the research. Orexin causes HIF-1 to switch cells to burn sugar using oxygen, so sugar is burned more efficiently.
"Our findings also bear relevance to obesity," Sikder said. "Our result shows that orexin promotes energy expenditure. Since body weight depends on the critical balance between food intake and energy expenditure, our results would predict that increased levels of orexin would make you lean, while the converse would make you obese. On the lighter side, a drug that promotes orexin's function would allow you to keep awake so that you can catch up with your buddies and party. The best part is that you will be able to eat your favorite food and still be lean."
Research conducted by UT Southwestern found that a lack of orexin is the cause of narcolepsy. "The findings buttress the idea that patients that lack orexin are narcoleptic," said Dr. Thomas Kodadek, who helped conduct the study. "If you can find a drug that substitutes for orexin, the strong prediction is that you can cure narcolepsy. Our results just emphasize this point."
Be the first to comment on this article!