A study in the journal Pediatric Research suggests that bright lights might play havoc with the internal body clocks of premature babies. Douglas McMahon, a researcher from Vanderbilt University, said that exposing baby mice to constant light keeps the master biological clock in their brains from developing properly and this can have a lasting effect on their behavior. While his study only worked with mice, McMahon believes the results might be applicable to premature babies being cared for in bright neonatal wards. About 14 million premature babies are born worldwide every year, and in developed nations, this means exposure to bright hospital lighting, usually around the clock. "We are interested in the effects of light on biological clocks because they regulate our physiology extensively, and also have an important effect on our mood," McMahon said. "This study suggests that cycling the lights in neonatal intensive care units may be better than constant lighting for premature babies' from the perspective of developing their internal clocks."
"Our understanding of light's effects on patients and staff is still very rudimentary," said William F. Walsh, chief of nurseries at Vanderbilt's Monroe Carrel Jr. Children's Hospital. "We need to know more. That is why studies like this are very important." Walsh explained that Vanderbilt's own neonatal intensive care unit (NICU) cycles its lighting in a day/night cycle and keeps lighting levels as low as possible. He added that covers were also kept over the isolet cots in an effort to duplicate the dark conditions of the womb.
The new study follows on from work published last year which found that long periods of constant light disrupt the synchronization of the biological clock in adult mice. In all mammals, including mice and humans, the master biological clock is located in an area of the brain that influences the activity of a surprising number of organs, including the brain, heart, liver and lungs; as well as regulating the daily activity cycles known as circadian rhythms.
McMahon is hoping to continue his research into the physiological effects that might be triggered by light patterns. "This is a new area of research," he said, "so there are a lot of unanswered questions. For example, could disruption of a baby's biological clock increase their vulnerability to associated mood disorders like depression and seasonal affective disorder? Could it make it harder for someone to adjust to shift work or suffer more from jet lag? All this is speculative at this point."
Source: Vanderbilt University
