A new study, published online in PLOS One, examined how a disruption in circadian rhythm is associated with a number of diseases, including intestinal issues such as obesity, metabolic syndrome, and inflammatory bowel disease. A model of chronic disruption of circadian rhythm was conducted in mice to demonstrate this association. Researchers note that this does not demonstrate that a similar association exists in humans.

Mice that ate a high-fat, high-sugar diet and had their circadian rhythms disrupted had more inflammation-causing bacteria than did the mice that had their rhythms disrupted and were fed the standard diet. For individuals that must maintain an irregular sleep schedule, such as firefighters, doctors, and policemen, ensuring a healthy diet can offset some of the negative impacts.

According to the National Institute of General Medical Sciences, circadian rhythms are most well-known for regulating sleep.  However, they also regulate other physical, behavioral, and mental changes that occur over a period of 24 hours. The circadian rhythms respond primarily to light and darkness, generally causing sleepiness during darkness.

The American Academy of Sleep Disorders identifies a number of conditions that can disturb the circadian rhythm.  For example, delayed sleep phase disorder results in going to sleep at least two hours later and waking up later in the morning.  The opposite condition, advanced sleep phase disorder, results in going to sleep and waking up several hours earlier.  Finally, irregular sleep-wake rhythm is a general term that refers to any undefined disturbance in the rhythm.