Sleep needs in individuals vary tremendously and changes during the life cycle. Newborn child sleeps for 14 - 18 hours during early months of infancy. Then by the age of 10 years, it drops to 9 -10 hours. For adult person, good sound sleep of 7 - 8 hours is sufficient. As one get older sleep diminishes to an average of 5 - 6 hours.
Insomnia becomes a serious problem when it affects daytime performance and behaviour.
Medical problems can cause sleeplessness. Physical pain from arthritis, ulcers, migraines, angina, breathing disorders like asthma, and respiratory problems such as cold and cough, irregular heart-beat or palpitation, cramps in legs, increased frequency of urination due to diabetes mellitus etc. Many types of drugs may lead to insomnia such as stimulants, sedative and antidepressants, drugs acting on thyroid, contraceptives etc. can cause insomnia. Alcohol consumption also causes disturbance in sleep. Both sleeping pills and alcohol lead to fragmented sleep and frequent early awakening instead of good sound sleep.