Sleep interrupted: What's keeping us up at night?

August 6, 2019

Science Daily/Florida Atlantic University

One of the largest longitudinal studies to date examined evening consumption of alcohol, caffeine and nicotine among an African-American cohort and objectively measured sleep outcomes in their natural environments instead of laboratory or observatory settings. The study involved 785 participants and totaled 5,164 days of concurrent actigraphy and daily sleep diaries that recorded how much alcohol, caffeine or nicotine they consumed within four hours of bedtime. Results may be good news for coffee lovers, bad news for smokers.

Between 50 to 70 million Americans have a sleep disorder. Sleepless nights are associated with a number of adverse health outcomes including heart disease, high blood pressure, diabetes, and certain cancers. Evening use of alcohol, caffeine and nicotine are believed to sabotage sleep. Yet, studies examining their effects on sleep are limited by small sample sizes that don't represent racial and ethnic diversity or objective measures of sleep. Furthermore, these investigations have been conducted in laboratory or observatory settings.

Considering the public health importance of getting a good night's sleep and the widespread use of these substances, relatively few studies have thoroughly investigated the association between evening use of alcohol, caffeine and nicotine and sleep parameters.

A study led by a researcher at Florida Atlantic University with collaborators from Brigham and Women's Hospital, Harvard T. H Chan School of Public Health, Harvard Medical School, Emory University the National Institutes of Health, and the University of Mississippi Medical Center, is one of the largest longitudinal investigations to date to examine evening consumption of alcohol, caffeine and nicotine among an African-American cohort with objectively measured sleep outcomes in their natural environments.

Using actigraphy (wrist-watch-like sensor) and concurrent daily sleep diaries, the researchers examined the night-to-night associations of evening use of alcohol, caffeine and nicotine on sleep duration, sleep efficiency and wake after sleep onset. The study involved 785 participants and totaled 5,164 days of concurrent actigraphy and daily sleep diaries that recorded how much alcohol, caffeine or nicotine they consumed within four hours of bedtime.

Results of the study, published in the journal Sleep, may be good news for coffee lovers. The researchers did not find an association between consumption of caffeine within four hours of bedtime with any of the sleep parameters. However, the researchers warn that caffeine dosing, and individual variations in caffeine sensitivity and tolerance, were not able to be measured and can play an important role in the association between caffeine use and sleep.

For smokers and those who enjoy "Happy Hour" or an alcoholic beverage with dinner, the study shows that a night with use of nicotine and/or alcohol within four hours of bedtime demonstrated worse sleep continuity than a night without these substances, even after controlling for age, gender, obesity, level of education, having work/school the next day, and depressive symptoms, anxiety, and stress.

Nicotine was the substance most strongly associated with sleep disruption and yet another reason to quit smoking. There was a statistically significant interaction between evening nicotine use and insomnia in relation to sleep duration. Among participants with insomnia, nightly nicotine use was associated with an average 42.47-minute reduction in sleep duration. The effects of nicotine may be particularly significant among individuals with insomnia.

The results from this study are especially meaningful as they were observed in individuals unselected for sleep problems and who generally had high sleep efficiency. Moreover, they were based on longitudinal data so that the associations can take account of not only between-person differences but also within-person variations in exposures and covariates such as age, obesity, educational attainment, having work/school the next day, and mental health symptomatology.

"African Americans have been underrepresented in studies examining the associations of nicotine, alcohol, and caffeine use on sleep," said Christine E. Spadola, Ph.D., lead author and an assistant professor in FAU's Phyllis and Harvey Sandler School of Social Work within the College for Design and Social Inquiry. "This is especially significant because African Americans are more likely to experience short sleep duration and fragmented sleep compared to non-Hispanic Whites, as well as more deleterious health consequences associated with inadequate sleep than other racial or ethnic groups."

These findings support the importance of sleep health recommendations that promote the restriction of evening alcohol and nicotine use to improve sleep continuity.

https://www.sciencedaily.com/releases/2019/08/190806101604.htm

Poor sleep at night, more pain the next day

January 29, 2019

Science Daily/Society for Neuroscience

After one night of inadequate sleep, brain activity ramps up in pain-sensing regions while activity is scaled back in areas responsible for modulating how we perceive painful stimuli. This finding provides the first brain-based explanation for the well-established relationship between sleep and pain.

In two studies -- one in a sleep laboratory and the other online -- Matthew Walker and colleagues show how the brain processes pain differently when individuals are sleep deprived and how self-reported sleep quality and pain sensitivity can change night-to-night and day-to-day. When the researchers kept healthy young adults awake through the night in the lab, they observed increased activity in the primary somatosensory cortex and reduced activity in regions of the striatum and insula cortex during a pain sensitivity task. Participants in the online study, recruited via the crowdsourcing marketplace Amazon Mechanical Turk, reported increased pain during the day after reporting poor sleep the night before.

These results suggest improving sleep quality, especially in hospital settings, could be an effective approach for pain management. More generally, the research highlights the interrelationship between sleep and pain, which is decreasing and increasing, respectively, in societies around the world.

https://www.sciencedaily.com/releases/2019/01/190129093714.htm

Adequate Sleep Helps Weight Loss

September 17, 2012

Science Daily/Canadian Medical Association Journal

Adequate sleep is an important part of a weight loss plan and should be added to the recommended mix of diet and exercise, states a commentary in CMAJ (Canadian Medical Association Journal).

Although calorie restriction and increased physical activity are recommended for weight loss, there is significant evidence that inadequate sleep is contributing to obesity. Lack of sleep increases the stimulus to consume more food and increases appetite-regulating hormones. “Sleep should be included as part of the lifestyle package that traditionally has focused on diet and physical activity."

"The solution [to weight loss] is not as simple as 'eat less, move more, sleep more,'" write Drs. Jean-Phillippe Chaput, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario and Angelo Tremblay, Laval University, Québec, Quebec.

"However, an accumulating body of evidence suggests that sleeping habits should not be overlooked when prescribing a weight-reduction program to a patient with obesity. Sleep should be included as part of the lifestyle package that traditionally has focused on diet and physical activity."

http://www.sciencedaily.com/releases/2012/09/120917123926.htm