Had a holter monitor that showed that my heart rate dropped to 39 at night, but holter was shown as normal. i always thought a heart rate that low was bad. in good shape, but don't do much exercise. heart rate is normal range during day. any concern?

If you are symptomatic, this may reflect a problem, but often there are technical reasons during lengthy monitoring. Please follow up.

A heart rate low of 39/min only at night (presumably while in bed) can be normal, especially if there is no associated dizziness. Perhaps it's worthwhile to check ones pulse at rest and immediately after a short brisk walk. If the heart rate increases significantly with exercise, and if one is having no symptom, then the low heart rate at night is probably normal.