While many people have difficulty sleeping from time to time, some people suffer from repeated problems getting to sleep or staying asleep. This affects their mood, their ability to get along with others, and their performance of everyday tasks. Sleep disturbances of this magnitude are commonly called insomnia. Bouts of insomnia that last no more than a few days or a few weeks are considered transient. Chronic insomnia afflicts sufferers on most nights for a month or more.