it may be secondary to chronic pain syndromes etc, acid reflux disease, etc, related to any medicines that you might be taking like anti
asthma, stimulants, anti hypertensive, etc. treatment might include cognitive behavioral therapy, rest, regular exercises and deep breathing exercises, drugs including benzodiazepine sedatives, like temazepam, non benzodiazepines like zolpidem, etc.Hope this helps. Take care.