Background: Insomnia is most often just a symptom of depression. However, a growing body of evidence suggests that insomnia is not just a symptom of depression, but that it may actually precede depression. Aim: The aim of the present study was to explore relation between insomnia and depression. Material and method: Research was carried out within the Greek and international bibliography. We used the Web data base including –medline/pubmed, wikipedia, medscape- with key-words: insomnia, relationship, depression, primary care. Results: Insomnia is an extremely common condition with major social and economic consequences worldwide. In spite of its prevalence and significant negative impact on the quality of life, insomnia receives inadequate attention from health authorities and physicians. Conclusion: The new findings are especially significant because they suggest that targeted treatment for insomnia will increase the likelihood and speed of recovery from depression.