If your goal is simply staying fit, both experts and science say that the best time to exercise is whatever hour allows you to do so consistently, regardless of where it falls on the clock. For certain goals, however, when you work out is a factor to consider.
The benefits of morning workouts
We know from research that people who exercise in the a.m. tend to get more movement in overall. Your naturally higher cortisol levels in the morning make it easier to recruit energy reserves early on than later in the day. Studies also show links between morning workouts and lower blood pressure in people with hypertension.
If you have a hard time getting motivated to work out, doing it first thing may help you get over the hump. “Morning is the time of day where our dopamine is at its highest, and there’s a lot of cognitive reserve built up throughout the night that enables us to want to push further at the gym rather than at night,” says Louisa Nicola, a neurophysiologist and female human performance expert for Momentous.
Another great benefit of working out in the morning, rather than the evening, is that it helps you sleep better, according to Nicola. “It helps prime your circadian clock,” she says.
But, if evenings are the only time you can exercise, that’s all right. “There is always a benefit to working out, so if you have to do it in the evening, that is okay,” Nicola says. The key is understanding how to tweak your p.m. routine so that it doesn’t mess with your sleep.
How to optimize evening workouts
Firstly, it’s important to understand why evening workouts can work against you. “When you work out, your body releases many hormones and you activate your sympathetic ‘fight or flight’ nervous system, which can interfere with a wind-down routine, which then interferes with sleep,” Nicola says. “The entire circadian rhythm may be disrupted as well, depending on the time you eat dinner.” This primarily happens because both eating and exercising elevate your body temperature, which would otherwise be lowering as your body prepares for bed.
The best way around this is timing your workouts so that you’re able to finish eating dinner at least 1.5 to two hours before going to sleep, Nicola says. “You don’t want to be working out at 9 p.m., whether it’s cardio or weights. That will disrupt sleep and throw you off the following day,” she says—unless you are a serious night owl.
So what does this mean for the majority of American exercisers? “If you can get the workout in at 6 p.m., that provides ample time to rest, recover, eat dinner, and prepare for sleep.”