Irregular sleep schedules associated with higher body mass and insulin resistance

insulin resistance:

In insulin resistance, muscle, fat, and liver cells do not respond properly to insulin and thus cannot easily absorb glucose from the bloodstream. As a result, the body needs higher levels of insulin to help glucose enter cells.

The beta cells in the pancreas try to keep up with this increased demand for insulin by producing more. As long as the beta cells are able to produce enough insulin to overcome the insulin resistance, blood glucose levels stay in the healthy range.

Over time, insulin resistance can lead to type 2 diabetes and prediabetes because the beta cells fail to keep up with the body’s increased need for insulin. Without enough insulin, excess glucose builds up in the bloodstream, leading to diabetes, prediabetes, and other serious health disorders.

Healthy sleep habits can make a big difference in your quality of life. Having healthy sleep habits is often referred to as having good “sleep hygiene.”Try to keep the following sleep practices on a consistent basis:

  1. Stick to a sleep schedule of the same bedtime and wake up time, even on the weekends. This helps to regulate your body’s clock and could help you fall asleep and stay asleep for the night.
  2. Practice a relaxing bedtime ritual. A relaxing, routine activity right before bedtime conducted away from bright lights helps separate your sleep time from activities that can cause excitement, stress or anxiety which can make it more difficult to fall asleep, get sound and deep sleep or remain asleep.

    If you have trouble sleeping, avoid naps, especially in the afternoon. Power napping may help you get through the day, but if you find that you can’t fall asleep at bedtime, eliminating even short catnaps may help.

  3. Exercise daily. Vigorous exercise is best, but even light exercise is better than no activity. Exercise at any time of day, but not at the expense of your sleep.
  4. Evaluate your room. Design your sleep environment to establish the conditions you need for sleep. Your bedroom should be cool – between 60 and 67 degrees. Your bedroom should also be free from any noise that can disturb your sleep. Finally, your bedroom should be free from any light. Check your room for noises or other distractions. This includes a bed partner’s sleep disruptions such as snoring. Consider using blackout curtains, eye shades, ear plugs, “white noise” machines, humidifiers, fans and other devices.
  5. Sleep on a comfortable mattress and pillows. Make sure your mattress is comfortable and supportive. The one you have been using for years may have exceeded its life expectancy – about 9 or 10 years for most good quality mattresses. Have comfortable pillows and make the room attractive and inviting for sleep but also free of allergens that might affect you and objects that might cause you to slip or fall if you have to get up during the night.
  6. Use bright light to help manage your circadian rhythms. Avoid bright light in the evening and expose yourself to sunlight in the morning. This will keep your circadian rhythms in check.
  7. Avoid alcohol, cigarettes, and heavy meals in the evening. Alcohol, cigarettes and caffeine can disrupt sleep. Eating big or spicy meals can cause discomfort from indigestion that can make it hard to sleep.  If you can, avoid eating large meals for two to three hours before bedtime. Try a light snack 45 minutes before bed if you’re still hungry.
  8. Wind down. Your body needs time to shift into sleep mode, so spend the last hour before bed doing a calming activity such as reading. For some people, using an electronic device such as a laptop can make it hard to fall asleep, because the particular type of light emanating from the screens of these devices is activating to the brain. If you have trouble sleeping, avoid electronics before bed or in the middle of the night.
  9. If you can’t sleep, go into another room and do something relaxing until you feel tired. It is best to take work materials, computers and televisions out of the sleeping environment. Use your bed only for sleep and sex to strengthen the association between bed and sleep. If you associate a particular activity or item with anxiety about sleeping, omit it from your bedtime routine

A new study suggests that frequent shifts in sleep timing may be related to adverse metabolic health among non-shift working, midlife women.

Results show that greater variability in bedtime and greater bedtime delay were associated with higher insulin resistance, and greater bedtime advance was associated with higher body mass index (BMI). In prospective analyses, greater bedtime delay — for example, staying up 2 hours later than usual — also predicted an increase in insulin resistance 5 years later. The cross-sectional and prospective associations between these measures were significant only when both weekdays and weekends were included in the analysis, suggesting that large deviations in bedtime between work days and free days contributed to impaired glucose regulation.

“Irregular sleep schedules, including highly variable bedtimes and staying up much later than usual, are associated in midlife women with insulin resistance, which is an important indicator of metabolic health, including diabetes risk,” said senior author Martica Hall, PhD, professor of psychiatry at the University of Pittsburgh. “We found that weekday-weekend differences in bedtime were especially important.”

Study results are published in the February issue of the journal Sleep.

“This study emphasizes the important health benefits of keeping a regular sleep schedule,” said American Academy of Sleep Medicine President Dr. Nathaniel Watson, who was not involved in the study. “In addition to sleeping 7 or more hours per night on a regular basis, adults should strive to maintain a consistent schedule by going to bed and waking up at the same times on weekdays and weekends.”

Led by Hall and lead author Briana J. Taylor, the research team analyzed data from the SWAN Sleep Study, an ancillary project to the Study of Women’s Health Across the Nation (SWAN). The community-based sample comprised 370 Caucasian, African American and Chinese non-shift working women between the ages of 48 and 58 years. Daily diary-reported bedtimes were used to calculate four measures of sleep timing: mean bedtime, bedtime variability, bedtime delay and bedtime advance. BMI and insulin resistance were measured at baseline and again an average of 5 years later.

“The results are important because diabetes risk increases in midlife women,” said Hall. “Our study suggests that irregular sleep schedules may be an important piece of this puzzle. The good news is that sleep timing is a modifiable behavior. Metabolic health was better in women who had more regular sleep schedules, including regular bedtimes across weekdays and weekends.”

According to the authors, irregular bedtime schedules expose the body to varying levels of light, which is the most important timing cue for the body’s circadian clock. By disrupting circadian timing, bedtime variability may impair glucose metabolism and energy homeostasis.

The authors suggest that future studies of sleep timing and metabolic health should examine potential mechanisms including melatonin as well as other hormones that are relevant to metabolic health and sensitive to circadian misalignment, including leptin, ghrelin and cortiso

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