Many of my patients with insomnia are understandably worried about the physical effects of insomnia. They are concerned that their insomnia will lead to cardiovascular disease (heart attack or stroke, for example) or death. To date, no studies have convincingly shown that primary insomnia increases risk of physical problems - it has been shown to increase rates of depression.
Here is an article about a study trying to link insomnia to increased risk of heart attack and stroke. However, the study authors did not separate the different types of insomnia, meaning the results are difficult to interpret. More specifically, they did not separate the effects of primary insomnia from secondary insomnia (as from sleep apnea) and even people who just decide to get too little sleep. Since the last two categories of insomnia can increase cardiovascular risk, it could make all insomnia seem risky, but this is artificial.