Yes, it can be the root cause in obstructional sleep apnea. Additional fat around the neck can make the airway narrower, thus creating an obstruction. Currently in the U.S. weight related sleep apnea is the number one cause. For people with mild to moderate weight related sleep apnea the treatment method is a weightloss program. There are also numerous other reasons outside of weight that obstructional sleep apnea occur.
The relationship between obesity and sleep apnea suspected of having obesity has a channel or narrower airway due to fat accumulation in several muscles around the airway. Other than that, the base of their tongue is also thought to be easier to push back and clog the airway when sleeping.
Sleep apnea causes poor quality sleep that makes you tired during the day and is one of the main causes of excessive daytime sleepiness. Sleep apnea is often undiagnosed. Most people who experience sleep apnea do not know they have it because it only occurs during sleep.