Are electric blankets safe to use overnight?

Electric blankets can be safe to use overnight in some cases, but they are not the default-safe choice for everyone. The safest general advice is to preheat the bed, then turn the blanket off before falling asleep, unless the manufacturer specifically says the model is approved for all-night use.

If you do use one overnight, choose a modern blanket with overheat protection and an automatic shut-off, and make sure it is in good condition and used exactly as directed. Do not use it if it is folded, bunched up, damaged, or covered by heavy bedding that could trap heat. Avoid overnight use for infants, small children, people who cannot sense heat well, or anyone with reduced sensation.

So: electric blankets can be used safely in some situations, especially newer models with automatic shut-off, but leaving one on all night is not automatically safe for every blanket or every person. Check the user manual for your exact model and follow it exactly.