Irregular sleep patterns increase risk of diabetes and obesity in shift workers, new study published in the journal Science Translational Medicine says.

The study conducted at Brigham and Women’s Hospital reinforces the findings that too little or disturbed sleep patterns may lead to increased risk of diabetes and obesity. There are plenty of studies that link diabetes type-2 and obesity to disturbed sleep patterns. But, this new study provides support by examining the participants in controlled lab environment and altering the timing of sleep, mimicking shift work or recurrent jet lag.

The study included 21 healthy participants who were confined in a controlled lab for six weeks. Researchers controlled timing of sleep, diet and other activities of the participants.

The participants first got optimal amount of sleep (approximately 10 hours per day). This was followed by three weeks of 5.6 hours sleep in a 24-hour period and with sleep occurring at all times of day and night. This was done to simulate the pattern of sleep of a shift-worker. Thus, this period saw participants sleep at irregular times within their circadian cycle.

Circadian cycle is the body’s internal clock that regulates sleep and many other processes in the human body.

The study closed with the participants having nine hours of recovery sleep at the usual time.

The researchers saw that prolonged sleep restriction with simultaneous circadian disruption decreased the participants’ resting metabolic rate. Moreover, during this period, glucose concentration in the blood increased after meals, because of poor insulin secretion by the pancreas.

A decreased metabolic rate could translate into a yearly weight gain of 10 pounds if the diet and activity are unchanged. Poor insulin secretion could lead to increased risk of diabetes.

“We think these studies support the findings from studies showing that, in people with a pre- diabetic condition, shift workers who stay awake at night are much more likely to progress to full-on diabetes than day workers,” said Orfeu Buxton, the lead study author.” Since night workers often have a hard time sleeping during the day, they can face both circadian disruptions working at night and insufficient sleep during the day. The evidence is clear that getting enough sleep is important for health, and that sleep should be at night for best effect.”

The Centers for Disease Control and Prevention (CDC) reports that in 2004 data from the Bureau of Labor Statistics, almost 15 million Americans work full time on evening shifts, night shifts, or other employer arranged irregular schedules.

National Geographic has reported that the demands of work, social activities and availability of 24-hourhome entertainment and internet access have caused people to sleep less now than in pre-modern times.

Lack of adequate amount of sleep as well as poor quality of sleep have been linked to depression, sleep apnea, hallucinations, headaches, irritability and more.

In a related study published in 2005, John McKinlay and team say “short and long sleep durations increase the risk of developing diabetes, independent of confounding factors. Sleep duration may represent a novel risk factor for diabetes.” The study reported that sleeping more than 8 hours per day could lead to type-2 diabetes.

According to the National Sleep Foundation’s 2010 Sleep in America Poll, majority of those surveyed get  a good night’s sleep a few nights per week or less, with some ethnic groups doing poorly than others. African-Americans report on getting the least amount of sleep and say that they need less sleep to function at their best.