Besides stress, there are other causes of insomnia such as decreased production of melatonin, asthma, arthritis, chronic pain, acid reflux, hyperthyroidism etc.
As Arvind stated there are many causes of insomnia besides stress, i think sleep disorders should be treated by sleep hygiene measures and psychotherapy if stress is the main cause, but you have to take into account that sleep disorders have strong negative effects on health and general cognition so if a patient is suffering them i would recommend to take medication and combine it with therapy, after a time you can partially remove the medication (if it's not needed).
While the location of errant sleep patterns may be the result of the matters above, each cause possibly individualistic, it seems its positioning as a cultural phenomenon is rarely investigated. Its imporatance is environmental, although its aetiology may lie elsewhere.
I suffered in the past and concluded: diet (too much coffee to begin with), needing to hit deadlines (environmental), habit. My cure-don't worry about it, its not important, I relaxed and caught up on my rest at other times and in other ways. As an independendent worker/freelance my time wasn't controlled by others (environment). As long ago sleep obtained through drugs was considered likely to be harmful as it probably does not affect the parts of the brain real sleep does-don't consider that as an option.
Being that stress is a major factor for many ailments, insomnia can be considered a disease even when is caused by stress. Although, of course, it is almost impossible to have one exclusive cause for a disease, there are usually multiple factors involved.
As a psychogist, I thinh that insomnia may have several reasons, chifley among them stress and anxiety. It can be treated with medication, meditation, psychoterapy and so forth. It is proved that sleeping well is a sine non condition for one's well- being.
Here is a link to my article on insomnia which appeared, in edited form, in Scientific American in Oct 2003: https://henry.olders.ca/wordpress/wp-content/uploads/2003/10/Insomnia-Diploma-course.pdf
Thank you Henry, thank you all, for valuable contributions.
Henry, the attitudes of insomniacs was interesting. And also, the reverse causality between mental health (depression and anxiety) and insomnia is very helpful. Thanx again.
I would consider even the tipology on insomnia, the quality of sleep when the patient actually sleeps and most of all what the patient intends for insomnia. Often there is a misperception on the actual quantity of sleep hours. As well, at first there are a few advices to help sleeping before eventual meds like avoiding electronic devices use and light, coffee and others sleep interfering factors etc. etc. Psychotherapy can help, but for a real severe insomnia can be not very helpful for the emergency of it, at least at the beginning