London: Sleeping with the lights on could leave you with a nasty hangover the next day, a study says.
Researchers have warned that the glow emitted by a TV or the reassuring presence of a night-light could actually impact on mental health.
It is the latest in a long line of warnings about the potential dangers of disrupting the body`s natural sleep-wake cycle, reports the Daily Mail.
Studies have also shown that working in night shifts can increase breast cancer risk. Last month, a study linked night-time light with weight gain.
Researchers from Ohio State University in US looked at the effects of exposing rodents to dim light during their sleeping hours.
At the equivalent of having a TV switched on in a darkened room, the lamp used was not bright, but it was enough to affect the animals` behaviour.
Those exposed to the dim light showed more symptoms of depression compared to the hamsters in the standard light-dark cycle.
Further tests showed differences in the structure of a brain region called the hippocampus.
Researcher Tracy Bedrosian from Ohio State University said: "The hippocampus plays a key role in depressive disorders, so finding changes there is significant. Even dim light at night is sufficient to provoke depressive behaviour."
Bedrosian`s colleague neuroscientist Randy Nelson said: "The light was a very low level. Something that most people could easily encounter every night."
They presented the findings at the Society for Neuroscience`s annual conference in US.