Normally, blood pressure follows a daily rhythm. It rises higher during the day and falls at night when we sleep. But what does it mean if you consistently have higher blood pressure at night than during the day? You could suffer from reverse dipping and face a higher risk of Alzheimer’s.

High blood pressure is known as the silent killer. But many of us, especially if we’re over 55, may be sleeping with the real silent killer: blood pressure that’s higher at night than during the day. Here’s what the research says and what you need to know to avoid being the next victim.