While laying down my heart rate is 83-85 is that normal?

Heart rate: The heart works harder when you lie flat compared with sitting up. This is more noticeable upon first lying down and after a minute or two the heart rate usually returns to normal in a healthy person. Persistently fast rates can be seen with overactive thyroid, certain heart problems, anemia, fever, exposure to stimulants like alcohol,caffeine,nicotine and some medications.