That nightlight may be affecting your sleep. Last year I had the opportunity to conduct a small experiment (N=15) on the effects of sleeping with a nightlight. The experiment was part of a research methods course in developmental psychology. I pretested 15 individuals from the class on three measures of cognitive abilities; verbal reasoning, numerical logic and short term working memory. After randomly assigning half of the group to sleep with a nightlight and half to sleep normally I retested the group. There actually were small detriments in the nightlight condition on measures of numerical logic and short-term memory.
There is an established link between poor sleep habits and reduced performance on various cognitive tasks (Tucker & Fishbein, 2009). Recent research findings have suggested a physiological pathway which would enable light to influence sleep and wakefulness via non- visual inputs to the mammalian brain (Hattar et al, 2002). At present the basis of most research into this pathway have been neuroanatomical in nature. The current study investigated the possible behavioural effects of sleeping with ambient room lighting. We examined a small subset of cognitive abilities in young adults before and after sleeping with a nightlight. Our results indicate that adults perform poorer on retests of numerical logic and memory after sleeping with a nightlight. These effects could potentially implicate our lives as prehospital care providers while sleeping during the day for a nightshift or grabbing a quick nap in a well lit station.