By not sticking to a regular bedtime and wakeup schedule and getting different amounts of sleep each night, you can put yourself at higher risk for obesity, high cholesterol, hypertension, high blood sugar and other metabolic disorders. For every hour of variability in time to bed and time asleep, a person may have up to a 27 percent greater chance of experiencing a metabolic abnormality, says a new study in the journal Diabetes Care.
Even after considering the amount of sleep a person gets - and other lifestyle factors - every one-hour, night-to-night difference in the time to bed or the duration of a night's sleep multiplies the adverse metabolic effect, the research shows. "Many previous studies have shown the link between insufficient sleep and higher risk of obesity, diabetes, and other metabolic disorders," says study author Tianyi Huang, Sc.D., epidemiologist of the Channing Division of Network Medicine at Brigham and Women's Hospital, Boston. "But we didn't know much about the impact of irregular sleep, high day-to-day variability in sleep duration and timing.”
Researchers followed 2,003 men and women - ages 45 to 84 - participating in the National Heart, Lung, and Blood Institute-funded (NHLBI) Multi-Ethnic Study of Atherosclerosis (MESA). The participants were studied for a median of six years to find out the associations between sleep regularity and metabolic abnormalities. To ensure objective measurement of sleep duration and quality, participants wore actigraph wrist watches to closely track sleep schedules for seven consecutive days. They also kept a sleep diary and responded to standard questionnaires about sleep habits and other lifestyle and health factors. Participants completed the actigraphy tracking between 2010 and 2013 and were followed until 2016 and 2017. "Objective metrics and a big and diverse sample size are strengths of this study," added Michael Twery, Ph.D., director of the NHLBI's National Center on Sleep Disorders Research. "As is the study's ability to look not only at current factors, but to conduct a prospective analysis that allowed us to assess whether patterns of irregular sleep could be linked to future metabolic abnormalities."
In fact, there were such associations, proved correct as the researchers had hypothesized. Individuals with greater variations in their bedtimes and in the hours they slept had a higher prevalence of metabolic problems, and these associations persisted after adjusting for average sleep duration. This was also the case when they looked at the participants who developed metabolic disorders during the 6.3 years of follow up. The prospective results showed that the variations in sleep duration and bedtimes preceded the development of metabolic dysfunction. This provides some evidence supporting a causal link between irregular sleep and metabolic dysfunction.
Participants whose sleep duration varied more than one hour were more likely to be African-Americans, work non-day shift schedules, smoke, and have shorter sleep duration. They also had higher depressive symptoms, total caloric intake, and index of sleep apnea. Increasing sleep duration or bedtime variability was strongly associated with multiple metabolic and simultaneous problems such as lower HDL cholesterol and higher waist circumference, blood pressure, total triglycerides, and fasting glucose. "Our results suggest that maintaining a regular sleep schedule has beneficial metabolic effects," added study co-author Susan Redline, M.D., senior physician in the Division of Sleep and Circadian Disorders at Brigham and Women's Hospital. "This message may enrich current prevention strategies for metabolic disease that primarily focus on promoting sufficient sleep and other healthy lifestyles."
Shorter Sleep Can Lead To Dehydration
Last year, a Penn State University study highlighted the fact that most adults sleep for about six hour or less per night as opposed the prescribed eight hours of sleep - and are prone to being dehydrated. The findings also emphasized that individuals who feel unwell after a night of poor sleep should consider dehydration as a factor and not simply think that they need more sleep. They are advised to drink more water to reduce the effects.
Researchers have carried out various tests to try and look into how sleep affects our hydration status as well as the risk of dehydration of adults in the U.S. as well as China. In both the populations, adults who reported six hours of sleep had more concentrated urine and 16 to 60 percent higher odds of inadequate hydration compared to the adults who slept eight hours on a regular basis.
The major factor causing this is how the body’s hormonal system regulates hydration in the body. The regulation of the body’s hydration status is done by the hormone called vasopressin - a hormone released all day as well as during the night. "Vasopressin is released both more quickly and later on in the sleep cycle," says lead author Asher Rosinger, assistant professor of biobehavioral health at Penn State. "So, if you're waking up earlier, you might miss that window in which more of the hormone is released, causing a disruption in the body's hydration.”
Dehydration has a lot of adverse effects on the body’s system and functions, such as mood, cognition, and physical performance. If changes in your sleeping routine are not made, chronic and long-term dehydration can occur. This can lead to further problems like kidney stones and high risk of urinary tract infection. Your inability to get more than six hours of sleep per night could affect your hydration status. The study also suggests that your inability to get enough sleep - which makes you feel tired and uncomfortable the next day - can be can be cushioned by drinking extra water.
The National Health and Nutrition examination survey analyzed two samples of adults. The Chinese Kailuan Study analyzed another sample. The samples involved over 20,000 adults. Participants were surveyed about their sleeping habits and in turn provided urine samples for analysis by the researchers for biomarkers of hydration. The data from this research is mainly observational and is from cross-sectional studies. For further studies, the same methodology should be used across sites where they can examine the relationship over a week to understand baseline sleep and hydration status.