Engaging in strenuous physical activity close to bedtime can negatively impact sleep quality, according to Dr. Shelby Harris, a behavioral sleep medicine specialist. The intensity and timing of workouts play crucial roles in how they affect the body's ability to rest.
A study analyzing millions of nights of sleep indicated a correlation between more strenuous workouts and later sleep onset, reduced total sleep time, and increased sleep disruption. According to Harris, vigorous exercise can elevate the body's alertness, making it difficult to wind down and transition into sleep.
Activities like high-intensity interval training, intense running, or demanding cycling can interfere with the body's natural cooling process and heart rate reduction, which are essential for deep sleep. Harris clarifies that the intensity, rather than the type of cardio, is the key factor. An easy jog or a relaxed bike ride may have a different effect on sleep compared to sprint intervals or a high-intensity class.
Signs that a workout was too stimulating include heavy breathing, a racing heart, and feeling energized 30 to 60 minutes post-exercise. Harris suggests that individuals experiencing these effects should consider moving their workouts earlier in the day. She recommends a minimum of two hours between finishing a vigorous workout and going to bed to allow the body adequate time to recover.
Mistakes in workout supplementation can also hinder sleep. Consuming caffeine before bed, often found in pre-workout products, can remain in the system for hours and disrupt sleep. Other ingredients, such as synephrine, yohimbine, or high doses of green tea extract, can increase alertness and interfere with rest. Harris advises careful label reading for any supplements taken later in the day, as even those marketed as natural energy boosters can have stimulating effects.
Conversely, moderate exercise and low-intensity activities can promote better sleep. Restorative yoga, stretching, light Pilates, or a casual walk can help reduce muscle tension and calm the nervous system, signaling the body to prepare for rest. These activities encourage slower breathing and relaxation, facilitating easier sleep onset. Moderate aerobic exercises like brisk walking, cycling, swimming, or jogging have also been consistently linked to improved sleep quality, helping individuals fall asleep faster and spend more time in deep, restorative sleep.