Obese rats have more broken up sleep and daytime sleepiness

Here is an article about a study presented at annual meeting of the Society for the Study of Ingestive Behavior. Researchers fattened rats with high fat diets and measured their sleep behavior. They found that the obese rats slept more in the daytime, indicating they were sleepier than normal rats. Also, the obese rates had more sleep fragmentation. Researchers think that obesity can reduce Orexin levels, which may increase sleepiness. This research supports other research showing that obesity alone increases daytime sleepiness.

Sleep Duration, Disinhibited Eating, and Weight Gain

Studies have been linking short sleep duration and weight gain in children and adults. Increased food consumption is thought to be responsible for this - short sleepers have more time awake to eat, especially at night. However, there is great variability in weight gain amongst short sleepers. A study was published in the Journal Sleep about short sleepers, disinhibited eating habits, and weight gain. Disinhibited eating examples include eating in response to a negative mood (emotional eating), overeating when others are eating, not being able to resist eating, and overeating because the food tastes good, rather than because of hunger.

The study participants consisted of 276 adults, aged 18 - 64 years old, who were followed for six years. They were nonsmokers, had stable body weight over the 6 months preceding testing, and have no metabolic disease (like diabetes or high blood pressure) or be on any medication that could confound the results. The participants were asked how many hours they slept per night, and divided into short sleeper (<6 hours per night), average sleeper (7-8 hours per night), and long sleeper (>9 hours per night). Disinhibited eating behavior was assessed via a validated eating questionnaire.

The results showed that those participants with high disinhibited eating patterns significantly increased their risk of overeating and gaining weight if they also had short sleep duration. As expected there was a relationship between increased total amount of food eaten and high disinhibited eating pattern. Interestingly, this relationship was only seen in short sleepers, and not seen in average and long sleepers.

OSA and Perioperative Complications in Bariatric Patients

Article in the British Journal of Anaesthesia about OSA and complications around the time of surgery in obese patients. Obese patients, with and without OSA, are at higher surgical risk. It's assumed that OSA is an independent risk factor for perioperative complications, but the article says there is not much objective data to support that.

Currently, bariatric surgeons typically have their patients have a sleep study prior to weight loss surgery. If there is significant OSA, than the patient is treated for several weeks to months with CPAP prior and upto the weight loss surgery.

The authors of this study studied patients that had a pre-op sleep study. Ninety-three percent of the patients with OSA received perioperative positive airway pressure therapy. All patients were closely monitored after operation. The overall complication rate was increased with open procedures compared with laparoscopic. In addition, increased BMI and age were associated with increased likelihood of pulmonary and other complications. Complication rates were not associated with OSA severity.

The authors concluded that in obese patients evaluated by sleep study before bariatric surgery and managed accordingly, the severity of OSA (the AHI), was not associated with the rate of perioperative complications. Thus, either OSA is not an independent risk factor for complications or the recognition and management of OSA in the perioperative period mitigates this risk. These results cannot determine whether unrecognized and untreated OSA increases risk.