It is impossible for your healthcare provider to know whether you will develop insomnia while taking Synthroid. Also, in some cases, if a person does develop insomnia, it is difficult to determine if these problems are because of other, unrelated reasons. The best way to determine whether your insomnia is caused by Synthroid is with a simple blood test.
If you develop insomnia while taking Synthroid, make sure to talk with your healthcare provider. He or she may be able to recommend other treatment options, such as adjusting your Synthroid dosage or suggesting a sleep medication.