From the Guidelines
Your high heart rate symptom from POTS (Postural Orthostatic Tachycardia Syndrome) likely improves at night because you're lying down, which eliminates the gravitational stress that triggers POTS symptoms when upright. When you're horizontal, blood can circulate more easily back to your heart without fighting gravity, reducing the need for your heart to beat faster to maintain blood pressure. Additionally, your parasympathetic nervous system (the "rest and digest" system) becomes more active at night, naturally lowering heart rate. The sympathetic nervous system (which increases heart rate) is typically less active during sleep. Fluid redistribution also plays a role - during the day, blood pools in your lower extremities when standing, but at night this pooling resolves. Your circadian rhythm naturally lowers heart rate during nighttime hours as well.
Key Factors
- Gravitational stress reduction when lying down
- Increased parasympathetic nervous system activity at night
- Decreased sympathetic nervous system activity during sleep
- Fluid redistribution and resolution of blood pooling in lower extremities
- Natural circadian rhythm effects on heart rate According to the 2022 ACC expert consensus decision pathway on cardiovascular sequelae of COVID-19 in adults 1, nonpharmacological interventions such as elevation of the head of one’s bed with 4–6-inch (10–15-cm) blocks during sleep can help address the pathophysiology of POTS. If your POTS symptoms are severe during the day, treatments might include increased salt and fluid intake, compression garments, exercise programs specifically designed for POTS, and medications like beta-blockers, fludrocortisone, or midodrine, but these should only be used under medical supervision.
Treatment Considerations
- Increased salt and fluid intake
- Compression garments
- Exercise programs specifically designed for POTS
- Medications like beta-blockers, fludrocortisone, or midodrine (under medical supervision)
From the Research
Pathophysiology of POTS
- POTS is a complex form of dysautonomia that presents with abnormal autonomic reflexes upon standing, leading to symptoms such as lightheadedness, tachycardia, fatigue, and cognitive impairment 2
- The pathophysiology of POTS is multifactorial, involving partial autonomic neuropathy, hypovolemia, and hyperadrenergic state 3
- Patients with POTS often exhibit overlapping characteristics from more than one of these mechanisms 3
Improvement of Tachycardia at Night
- There is no direct evidence in the provided studies to explain why tachycardia associated with POTS improves at night
- However, it is known that symptoms of POTS are worse when upright and improve in supine position 4
- This suggests that the improvement of tachycardia at night may be related to the change in posture, as patients are more likely to be in a supine position at night
Treatment of POTS
- Treatment of POTS is based on nonpharmacological measures and pharmacologic therapies that target the underlying pathophysiologic mechanism 5, 3
- Beta-blockers, ivabradine, and midodrine have been shown to be effective in reducing heart rate and improving symptoms in patients with POTS 2
- Proper medical treatment can improve dramatically the clinical and autonomic-hemodynamic disturbances observed in patients with POTS 6