Insomnia is not a disease, and no specific test can diagnose it. But it can make you feel bad, and it can affect your health. It can also be a sign of other problems. Your doctor may want to do blood tests to rule out certain medical conditions such as thyroid problems. "Normal sleep" differs for each person. Checking your health and sleep history is an important first step to finding a cause for poor-quality sleep. Talk with your doctor about your medical history and any medical problems you have or any medicines you are taking.
Your doctor can learn a lot about your insomnia and its causes by reviewing your sleep history. He or she can look at how long you sleep each night, how well you sleep, and what unusual behaviors you may have while sleeping, like snoring or gasping. Since you may be unaware of all your sleep problems while you sleep, your doctor may ask your bed partner questions about your sleeping behavior to better understand your sleep problems. He or she may also ask you to keep a sleep journal(What is a PDF document?) for 1 or 2 weeks to monitor your sleep patterns and habits. Your sleep journal can help your doctor spot certain habits that may affect your sleep, or even see signs of a hidden health problem that may need to be checked out.
If your doctor thinks that you have a sleep disorder, he or she may refer you for a sleep study. When you have a sleep study, you stay overnight in a special sleep lab.
Your doctor may recommend a sleep study if your insomnia seems to be caused by breathing problems (such as sleep apnea) or periodic limb movement disorder, or if you have tried other treatments that haven't worked.