Been told that power napping is bad for you. One should stay awake until bed time?

Napping. Not sure abut the context. In general napping unless you're < 5 or > 65 years old should not be necessary. However, we are a society that does not sleep enough hours and napping is much much safer than using medication including caffeine. This being said, if you suffer from insomnia, napping can be very harmful in disrupting sleep cycle. Power nap is 15 minutes or less to avoid deeper sleep.