A new warning from sleep specialist Dr. Leah Kaylor is sparking fresh debate about the best time of day to exercise, as emerging research shows working out in the evening could disrupt the quality of your sleep. Dr. Kaylor, speaking to the Daily Mail, highlighted that while exercise is essential for health, exercising too close to bedtime can keep both body and mind too “activated” for restful sleep, leaving many fitness enthusiasts wide awake when they should be drifting off (source: Daily Mail).
For Thai readers, the question of when to fit exercise into a busy schedule—often packed with long work hours, traffic, and family obligations—hits close to home. Many Thais find that the only available time for physical activity is after sundown. According to Dr. Kaylor, it’s exactly this pattern that may quietly be compromising both our health goals and much-needed rest.
Why does evening exercise disrupt sleep? Dr. Kaylor explains that any vigorous physical activity rapidly boosts heart rate, increases circulation, and floods the body with “action hormones” like adrenaline and cortisol. “These hormones prime you for action, not rest,” she notes. Moreover, a rise in core body temperature, a normal part of any workout, runs counter to the natural cooling signal your body looks for to initiate sleep. “If your body is still warm and alert from a late workout, it may take hours to return to a sleep-ready state,” Dr. Kaylor explains (Daily Mail).
These findings are echoed by recent scientific studies. A 2025 large-scale study published in Nature Communications followed nearly 15,000 active individuals over a year and found that those who ended their workouts less than four hours before sleep had noticeably shorter and lower-quality sleep, higher nighttime heart rates, and lower heart rate variability—both signs of poor overnight recovery (Nature Communications). Simply put, the later and harder you exercise, the less restorative your sleep is likely to be.
Importantly, even if you fall asleep quickly after an evening workout, lingering levels of adrenaline and cortisol may silently prevent you from reaching the deep and REM sleep stages critical for physical recovery, memory, and emotional resilience. Dr. Kaylor warns, “Your sleep becomes lighter, more fragmented and less restorative.”
Beyond the body, the brain can also remain highly engaged after exercise, replaying everything from perfect squat form to celebrating a new personal best. This mental “afterburn” can make it especially hard to truly switch off, something many Thais who juggle their own worries or nighttime chores may find familiar.
Yet, with so many juggling late office hours and home duties, shifting workouts to the morning isn’t always practical. What, then, should Thais with no choice but to exercise after dark do? Dr. Kaylor recommends aiming to finish any strenuous exercise at least three hours before bedtime whenever possible. For those with packed schedules, she suggests “exercise snacks”—short, 5-10 minute bursts scattered through the day. Research shows accumulating 150 minutes of moderate activity per week (even in small chunks) can yield substantial health and sleep benefits (Daily Mail; Monash University).
These recommendations align with long-standing “sleep hygiene” principles endorsed globally and by Thai sleep clinics alike: avoid physical and mental exertion close to bedtime, maintain a consistent sleep schedule, and create a cool, dark, quiet sleep environment, free of screens and bright lights (Wikipedia).
Interestingly, the traditional Thai approach of gentle evening movement—like ลมปราณ breathing exercises or light walking after dinner—may pose less risk. In contrast to strenuous HIIT or late-night weightlifting, these activities cause less of a spike in core temperature and adrenaline, making them a safer bedtime choice.
Culturally, the role of sleep in Thai society is often overlooked. While many Thais acknowledge “ความสำคัญของการนอน” (the importance of sleep), the realities of city life and social expectations can crowd out good sleep hygiene. The shift towards gym culture, 24-hour fitness centers, and “night owl” lifestyles means this dilemma of evening workouts versus restful sleep is more relevant than ever in Bangkok and other urban centers.
Looking ahead, as Thailand’s working population faces rising rates of metabolic syndrome, diabetes, and mental health challenges, ensuring both adequate movement and restorative sleep is crucial. There may be increasing interest in alternative workplace wellness models—such as short, structured exercise breaks during office hours (“exercise snacks”) or community-based fitness programs that align with natural circadian rhythms.
For now, practical advice for Thai readers is straightforward: if you can, time your workouts so they end at least three hours before bedtime, especially if they’re intense. If evenings are your only option, opt for gentle activity, and focus on a consistent wind-down routine—dim the lights, turn off screens, and allow your body to cool down naturally before sleep. For professionals, advocating for the ability to incorporate “movement breaks” at work could be a step towards both better productivity and sleep. Finally, parents should be mindful of late sport or dance classes for children, as young people’s brains are especially prone to sleep disruption.
In the end, both science and tradition agree: a healthy mind and body depend on balance, not just in the timing and intensity of movement, but in honoring the vital role sleep plays in our overall well-being.
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