While some people are up at the crack of dawn to lace up their running shoes, others can’t fathom a workout before noon.

When your priority is just to squeeze in some exercise, finding the perfect time can be as much about personal preference as it is physiology.

Still, you may wonder whether one time is better than another for reaching your best times on the treadmill or making gains at the weight bench.

Exercise is supposed to feel good — but if muscles are tight in the morning or working out too late disrupts your sleep, it can feel counterproductive. Here’s a look at the pros and cons of working out at different times of day.

Plenty of people tout the benefits of early morning sweat sessions, but if you can’t fit in a workout in the a.m., don’t sweat it (literally). There are plenty of reasons why exercising later in the day can be a smart choice.

You’re already warmed up

One factor in favor of a later workout is your body’s core temperature. Your body temp typically increases throughout the day, so muscle strength, flexibility, and endurance may peak in the late afternoon.Küüsma M, et al. (2016). Effects of morning versus evening combined strength and endurance training on physical performance, muscle hypertrophy, and serum hormone concentrations. DOI: 10.1139/apnm-2016-0271

A cold, just-rolled-out-of-bed body, on the other hand, leaves muscles stiff, inefficient, and susceptible to sprains.Castellani JW, et al. (2015). Cold stress effects on exposure tolerance and exercise performance. DOI: 10.1002/cphy.c140081

You may have a better reaction time

In younger adults, the afternoon is when reaction time is fastest, so it might be the best time for a game of “open-skill” sports like basketball and soccer that require quick thinking and moving.Knight M, et al. (2013). Look out! It’s your off-peak time of day! Time of day matters more for alerting than for orienting or executive attention. DOI: 10.1080/0361073X.2013.779197

Hormones can work to your advantage

Hormone levels also play a role in determining optimal workout time. Testosterone is important for muscle growth and strength — as well as stamina — in all genders.Hirschberg A, et al. (2019). Effects of moderately increased testosterone concentration on physical performance in young women. DOI: 10.1136/bjsports-2018-100525

The body may produce more testosterone during late afternoon resistance training than it does during morning workouts.Hayes LD, et al. (2010). Interactions of cortisol, testosterone, and resistance training: influence of circadian rhythms. DOI: 10.3109/07420521003778773

Plus, the stress hormone cortisol, which aids in the storage of fat and reduction of muscle tissue, peaks in the morning and decreases throughout the day and during exercise.Anderson T, et al. (2017). Exercise and the cortisol awakening response: A systematic review. DOI: 10.1186/s40798-017-0102-3

You may burn more calories

Finally, one study found that the body burns the most calories in the afternoon hours — so you could see a small return on weight loss efforts by hitting the gym after lunch.Zitting K. (2018). Human resting energy expenditure varies with circadian phase. DOI: 10.1016/j.cub.2018.10.005

But early birds, take heart: Morning workouts can be successful too.

When the alarm goes off, the last thing you probably want to do is roll out of bed, lace up your sneakers, and head to the gym. But there are some awesome advantages to a morning workout worth considering.

Your habit may be more consistent

We’ve all been there: the day starts and you think, “I’ll work out later, when I’m done with a few things.” But then the evening rolls around and what’s the one box on your to-do list left unchecked? Of course, it’s the gym.

Afternoon and evening workouts may conflict with other responsibilities as the day progresses. Plus, a full day’s work can take a serious toll on willpower, which can overcome any gym-goer’s best intentions.

You may find that it’s easier to keep a morning workout routine consistent. Head out the door before you even have time to second-guess yourself, and by the time you’re 100 percent awake, you’ll already be on the machines.

You may experience better sleep

Morning workouts might also be a good option for stress-free snoozing. Since exercise increases heart rate and body temperature, working out too late in the evening (generally after 8 p.m.) may disrupt sleep.

In fact, one study showed that working out at 7 a.m. (compared to 1 p.m. or 7 p.m.) helped some people sleep more soundly at night.Fairbrother K, et al. (2014). Effects of exercise timing on sleep architecture and nocturnal blood pressure in prehypertensives. DOI: 10.2147/VHRM.S73688

You’ll be less hungry

Several studies have also found that exercise can help curb appetite after working out.Gomez E, et al. (2017). Review and analysis of physical exercise at hormonal and brain level, and its influence on appetite. DOI: 10.1016/j.arteri.2017.04.002 If you’d like to keep hunger at bay later in the day, a morning workout might be for you.

You may burn more fat

It’s been proven, too, that people can burn significantly more body fat exercising on an empty stomach — much easier to do first thing in the a.m. than at night.Veira A, et al. (2016). Effects of aerobic exercise performed in fasted v. fed state on fat and carbohydrate metabolism in adults: a systematic review and meta-analysis. DOI: 10.1017/S0007114516003160

Research suggests the body could get used to regular gym dates, so if we hit the weight room every day at 4 p.m. (or any other time), eventually we might perform better then than at other times of day.Chtourou H, et al. (2012). The effect or training at a specific time of day. DOI: 10.1519/JSC.0b013e31825770a7

These findings are similar to other research, which suggests that the body could adapt to regular exercise by altering your circadian rhythm.Youngstedt S, et al. (2019). Human circadian phase-response curves for exercise. DOI: 10.1113/JP276943

If you know you’re predisposed to be a night owl or morning lark, you might use that info to your advantage.

One study found that quality of athletic performance often depends on how many hours have passed since your natural waking time.Facer-Childs E, et al. (2015). The impact of circadian phenotype and time since awakening on diurnal performance in athletes. DOI: 10.1016/j.cub.2014.12.036

The fact is, people who work out consistently at the same time of day see better results, regardless of whether they choose morning, noon, or night to hit the gym.Schumacher L, et al. (2019). Relationship of consistency in timing of exercise performance and exercise levels among successful weight loss maintainers. DOI: 10.1002/oby.22535

If working out in the morning is best for your schedule, just make sure to warm up muscles that might be cold and tight from sleep.

And to keep afternoon workouts consistent, treat them as unbreakable appointments, find a workout buddy, and keep a gym bag in the car or office to minimize excuses.

In the end, it’s most important to find a realistic, consistent workout schedule, no matter what the time.