Why Does Heart Rate Have to Drop Before Sleep?

Andrew Huberman says thoughts do not actually turn off until heart rate drops. The brain wants to think, plan, remember, and predict what comes next, so shutting that off is a skill. The gateway he describes is pure sensation: attention moving across the surface of the body, the feet, the legs, breathing, and the sounds in the room. Meditation is a different task. Meditation holds all attention on one target, such as the breath, a spot behind the forehead, or the hands.

Long exhales are what drop the rate, through respiratory sinus arrhythmia. The word arrhythmia sounds dangerous. The pattern is the opposite. The diaphragm moves, the lungs fill, the space around the heart changes, and an exhale is the moment the brain signals the heart to slow. An inhale speeds it up. Caffeine too late, and too much bright light late in the day, make the drop harder. Alcohol and cannabis can help a person get to sleep and still impair the quality of that sleep. A second requirement sits beside the heart rate: forgetting where the limbs are in space.