Children with fetal alcohol spectrum disorders exhibit altered sleeping and eating patterns, as well as other behavioral problems such as attention deficits and depression.
Alterations in these behaviors may indicate that their biological rhythms, which are controlled by circadian systems, have been affected by alcohol exposure during development. Rodent research confirms that alcohol exposure during a period equivalent to the third human trimester influences the ability to synchronize circadian rhythms to light cues.
Children with fetal alcohol spectrum disorders (FASD) suffer from a variety of behavioral alterations. For example, they may exhibit alterations in sleeping and eating patterns, which may indicate that their circadian systems - which control biological rhythms - have been affected by alcohol exposure during development. A rodent study in the May issue of Alcoholism: Clinical & Experimental Research confirms that alcohol exposure during a period equivalent to the third human trimester influences the ability to synchronize circadian rhythms to light cues.
"Human infants with FASD may suffer from sleep disorders, including a reduced amount of sleep, abnormal brain wave activity, and fragmented rapid eye movement and slow-wave sleep, which may be related, in part, to circadian dysregulation," explained Jennifer D. Thomas, associate professor of psychology at San Diego State University and corresponding author for the study. "Disruptions in circadian rhythms can also influence other behaviors, including attention and mood regulation. In fact, individuals with FASD may suffer from depression and other psychopathologies." Although sleeping, eating and mood can be influenced by many factors, she said, the circadian systems are responsible for coordinating multiple physiological systems with environmental cues.
"Most of our body processes are regulated in the circadian fashion," concurred David Earnest, a professor in the department of neuroscience and experimental therapeutics at Texas A&M University Health Sciences Center. "We know that these circadian rhythms are important in human health, although we still need to fully determine how alterations in circadian rhythmicity are linked to human mental and physical disorders."
For this study, researchers exposed male Sprague-Dawley rats to 6.0 g/kg of alcohol per day (n = 8), using an artificial rearing procedure, from postnatal days four through nine. The alcohol level represented heavy binge drinking. An artificially reared control group (n = 8) and a normally reared control group (n = 8) were also included in the study design. At 10 to 12 weeks of age, wheel-running behavior was continuously measured for eight days under a 12-hour light/12-hour dark (LD) cycle. Then the cycle was delayed by six hours and the rats were exposed to a new LD cycle for an additional six days. Their adjustment to the new cycle was evaluated.
"Our study demonstrated that exposure to alcohol during the third trimester, when components of the circadian system in the brain are developing, can lead to long-lasting alterations in the ability to entrain the cycles to environmental cues, like light/dark cycle," said Thomas. "These data suggest that dysfunction of circadian systems may contribute to some of the behavioral problems observed in children with FASD."