how do i lower my heart rate for sleep?

To lower your heart rate before sleep, emphasize a long, slow exhale; exhaling engages vagal pathways that slow the heart and promote calm. 1

• Physiological sigh: Inhale deeply through your nose, take a second short, sharp nasal inhale, then exhale slowly through your mouth until your lungs feel empty. 2
• Longer, stronger exhales: Make your exhales longer and/or more vigorous than your inhales to slow your heart rate and shift the autonomic nervous system toward calm. 3
• Regular practice: Deliberately extending your exhales during the day can strengthen the pathway involved in heart-rate control; the episode also notes that physical activity, including high-intensity interval training, can help maintain heart-rate variability. 4 5
• Relax the diaphragm actively: Actively relax your diaphragm as you exhale. If anxiety makes you especially aware of a racing heart, try one big, long exhale to slow it. 6

These are breathing and heart-rate tools; the evidence here does not establish that they treat an underlying cause of a persistently high heart rate.