I had them all the time when I was young. So bad and long (over an hour each and I would get about 1 a week) that my mom would take me to the doctor - about 5 times in total and they always said not to worry.
By the time I was 12 they slowed down to 1 a year.
When I was on stuff I would get them more often again - a blood pressure thing there.
The combination of dry air and higher blood pressure will definitely do it.