Is coffee good or bad for you?

Moderate intake (roughly 3–4 cups daily) is associated with slightly lower risk of type 2 diabetes, liver disease, and overall mortality. Downsides are disturbed sleep, anxiety, palpitations, and reflux. Pregnant women should stay under about 200 mg caffeine daily.

Up to about 400 mg of caffeine daily is considered safe for most adults — roughly 4 cups of brewed coffee, though strength varies a lot with preparation.

Caffeine has a half-life of about 5-6 hours, so an evening cup can still be affecting sleep at midnight even if you fall asleep normally.