Blood oxygen levels normally drop a small amount during sleep, but not to low levels unless there is an underlying problem. A period of low blood oxygen during sleep is defined as less than or equal to 88% blood oxygen saturation lasting for five or more minutes. There are a couple of reasons a person may experience low blood oxygen levelsAlthough alcohol's sedative effects can make you drowsy, they also have other effects that can interfere with quality sleep. Several hours after that nightcap, the alcohol raises the body's level of epinephrine, a stress hormone that increases the heart rate and generally stimulates the body, which can result in nighttime awakenings.
For many people, the drug helps curb anxiety and promote sleep. It can also make you feel drowsy and lightheaded and may make you less mentally alert, so operating machinery and motor vehicles is not recommended while taking Xanax until you know how it makes you feel. Other side effects of Xanax can include: Dry mouth.