When you go to bed and how long you sleep at a time might actually make it difficult for you to stop worrying, according to researchers at Binghamton University

The study, led by Binghamton Anxiety Clinic Director Meredith Coles and graduate student Jacob Nota, found that people who sleep for shorter periods of time and go to bed very late at night are often overwhelmed with more negative thoughts than those who keep more regular sleeping hours. People are said to have repetitive negative thinking when they have bothersome pessimistic thoughts that seem to repeat in their minds without the person feeling as though he or she has much control over these contemplations. They tend to worry excessively about the future, delve too much in the past and experience annoying intrusive thoughts. Such thoughts are often typical of people suffering from generalized anxiety disorder, major depressive disorder, post-traumatic stress disorder, obsessive-compulsive disorder and social anxiety disorder. These individuals also tend to have sleep problems. Previous studies have linked sleep problems with such repetitive negative thoughts, especially in cases where someone does not get enough shuteye. Nota and Coles set out to replicate these studies, and to further see if there's any link between having such repetitive thoughts and the actual time when someone goes to bed. They asked 100 young adults at Binghamton University to complete a battery of questionnaires and two computerized tasks. In the process, they measured how much the students worry, ruminate or obsess about something - three measures by which repetitive negative thinking is gauged. The students were also asked whether they were more habitual morning or evening types, preferring to hold regular hours or to have a sleep-wake schedule that is more skewed towards later in the day. The researchers found that people who sleep for shorter periods of time and go to bed later often experience more repetitive negative thoughts than others. This was also true for those students who described themselves as evening types. "Making sure that sleep is obtained during the right time of day may be an inexpensive and easily disseminable intervention for individuals who are bothered by intrusive thoughts," said Nota. The findings also suggest that sleep disruption may be linked to the development of repetitive negative thinking. Nota and Coles believe that it might benefit people who are at risk of developing a disorder characterized by such intrusive thoughts to focus on getting enough sleep. "If further findings support the relation between sleep timing and repetitive negative thinking, this could one day lead to a new avenue for treatment of individuals with internalizing disorders," added Coles. "Studying the relation between reductions in sleep duration and psychopathology has already demonstrated that focusing on sleep in the clinic also leads to reductions in symptoms of psychopathology." This study is part of a line of research examining the relations between sleep behavior and mental health. Based on growing evidence linking sleep and psychopathology, Nota and Coles and their colleagues at Binghamton University are aiming to understand how information about sleep may be used to help individuals with anxiety disorders. People who have sleep apnea or spend less time in deep sleep may be more likely to have changes in the brain that are associated with dementia, according to another study. The study found that people who don't have as much oxygen in their blood during sleep, which occurs with sleep apnea and conditions such as emphysema, are more likely to have tiny abnormalities in brain tissue, called micro infarcts, than people with higher levels of oxygen in the blood. These abnormalities are associated with the development of dementia. In addition, people who spent less time in deep sleep, called slow wave sleep, were more likely to have loss of brain cells than people who spent more time in slow wave sleep. Slow wave sleep is important in processing new memories and remembering facts. People tend to spend less time in slow wave sleep as they age. Loss of brain cells is also associated with Alzheimer's disease and dementia. For the study, 167 Japanese American men had sleep tests conducted in their homes when they were an average age of 84. All were followed until they died an average of six years later, and autopsies were conducted on their brains to look for micro infarcts, loss of brain cells, the plaques and tangles associated with Alzheimer's disease and Lewy bodies found in Lewy body dementia. The researchers divided the participants into four groups based on the percentage of time spent with lower than normal blood oxygen levels during sleep, with the lowest group spending 13% of their time or less with low oxygen levels and the highest group spending 72% to 99% of the night with low oxygen levels. Each group had 41 or 42 men. Of the 41 men in the lowest group, four had micro infarcts in the brain, while 14 of the 42 men in the highest group had the abnormalities, making them nearly four times more likely to have brain damage. Previous studies have also shown a link between sleep stages and dementia. For this study, the participants were again divided into four groups based on the percentage of the night spent in slow wave sleep. Of the 37 men who spent the least time in slow wave sleep, 17 had brain cell loss, compared to seven of the 38 men who spent the most time in slow wave sleep. The results remained the same after adjusting for factors such as smoking and body mass index and after excluding participants who had died early in the follow-up period and those who had low scores on cognitive tests at the beginning of the study. "These findings suggest that low blood oxygen levels and reduced slow wave sleep may contribute to the processes that lead to cognitive decline and dementia," said study author Rebecca P. Gelber, MD, DrPH, of the VA Pacific Islands Health Care System and the Pacific Health Research and Education Institute in Honolulu, Hawaii. "More research is needed to determine how slow wave sleep may play a restorative role in brain function and whether preventing low blood oxygen levels may reduce the risk of dementia." Gelber noted that a previous study showed that use of a continuous positive airway pressure machine (CPAP) for obstructive sleep apnea may improve cognition, even after dementia has developed. There was no association between the sleep measures and the level of plaques and tangles.