Does a sleep study in a clinic make sense, and when should you have one?

For ordinary sleep problems -- difficulty falling asleep or staying asleep -- a sleep study in a clinic is not necessary. A thorough conversation with your doctor, keeping a sleep diary and completing a questionnaire are sufficient for most people to reach a diagnosis and start treatment. A wrist-worn device that estimates your sleep (actigraphy) is equally unhelpful for the standard diagnosis of insomnia, although it can help distinguish between different sleep disorders.

A sleep study does have clear added value when there is suspicion of another sleep disorder alongside insomnia. Think of sleep apnea, in which breathing repeatedly stops briefly during the night, or restless legs syndrome, in which the legs move periodically during sleep. A clinic-based sleep study is also recommended for insomnia that does not respond to treatment, in order to identify an underlying cause.

In children in whom sleep apnea is suspected and who are considering a tonsil operation, a sleep study is strongly recommended when risk factors are present. These include, for example, obesity, Down syndrome, abnormalities of the head or jaw, neuromuscular conditions or sickle cell disease. Extra measurement is also worthwhile when the complaints do not correspond well with what the doctor finds during examination.

Pregnant women form another special group. In the final part of pregnancy, studies using full sleep assessments show that between 17 and 45 percent of women have a sleep-related breathing disorder. Snoring alone is not a reliable signal: it says too little to serve as a screening test.