Prognosis

Insomnia and Depression. Although stress and depression are major causes of insomnia, insomnia may also increase the activity of the hormones and pathways in the brain that can produce emotional problems. Even modest alterations in waking and sleeping patterns can have significant effects on a person's mood. Persistent insomnia may even predict the future development of emotional disorders. Some investigators are exploring the possibility of preventing psychiatric disorders by early recognition and treatment of insomnia.

Effects on Physical Health

Effects on the Heart. Although there has been some concern that insomnia may increase the risk for heart problems, little evidence has supported any significant dangers. One study reported signs of heart and nervous system activity in people with chronic insomnia that might place such individuals at risk for coronary heart disease. If it exists, however, this increased danger is very modest compared with other risk factors for heart disease. Yet another report suggested that sleep complaints in elderly people without coronary artery disease predicted a first heart attack. Sleep disorders in such cases may have been a marker for depression, however, which is a risk factor for heart attacks in elderly people.

Effects on Weight. Lack of sleep can cause weight gain and obesity. In a 16-year study of over 68,000 women, those who slept no more than 5 hours a night were 32% more likely to gain at least 33 pounds, and those who slept 6 hours had a 12% increased risk of weight gain compared to women who slept at least 7 hours a night.

Effects on the Immune System. A 2003 study reported significant differences in immune factors among sleepers, with higher levels of certain infection-fighters observed in good sleepers than in people with chronic insomnia. The significance of these findings is still unknown, however.