Many people like to start their day with a morning run for a variety of reasons. For example:

  • The weather is often cooler in the morning, thus more comfortable for running.
  • Running in the light of day may feel safer than running after dark.
  • A morning workout may provide an energy boost to help kickstart the day.

On the other hand, running in the morning isn’t always appealing. Many people prefer to run in the evening for one or more of the following reasons:

There are also researched-based reasons to run — or not to run — in the morning, including its effect on:

  • sleep
  • performance
  • circadian rhythm
  • weight management

Intrigued? Here’s what you need to know.

One reason to run in the morning is that it may lead to a better night’s sleep.

According to a 2014 study of people working out at 7 a.m., 1 p.m., and 7 p.m., those involved in aerobic exercise at 7 a.m. spent more time in deep sleep at night.

A 2012 study of 51 adolescents with a mean age of 18.3 years also reported improved sleep and psychological functioning in those who ran every weekday morning for 3 consecutive weeks.

If you’re primarily running as a means of basic exercise, it probably doesn’t matter what time of day you run, as long as you have a consistent program.

In fact, a 2012 review published in the Journal of Strength & Conditioning Research indicates that the regularity of training in either morning or evening has a greater impact on performance than the time of day selected.

But if you’re training for performance, a 2009 study of cyclists showed that 6 a.m. workouts didn’t result in as high a performance as 6 p.m. workouts. More research is needed to fully understand these findings.

According to a 2016 study published in the Journal of Human Kinetics, athletes have a tendency to pick sports with training times that match their circadian rhythm.

In other words, if you’re a morning person, you’re more likely to select a sport that typically trains in the morning.

This, in turn, will affect when you choose to schedule your training for a sport like running that doesn’t necessarily have a traditional training time.

When you wake up in the morning with an empty stomach, your body is reliant on fat as a primary source of food. So if you run in the morning before you eat breakfast, you’ll burn fat.

However, 2014 study published in the Journal of the International Society of Sports Nutrition concluded that there was no difference in fat loss among those who exercised after food and those who exercised in a fasting state.

If you’re running before the sun comes up or after the sun goes down, you may want to consider the following safety precautions:

  • Choose a well-lit area for your run.
  • Wear reflective shoes or clothing.
  • Don’t wear jewelry or carry cash, but do carry identification.
  • Let someone know where you’re going to run, as well as the time you expect to return.
  • Consider running with a friend, family member, or other running group.
  • Avoid wearing earphones so that you can stay alert and tuned in to your surroundings. If you do wear earphones, keep the volume low.
  • Always look both ways before crossing the street, and obey all traffic signs and signals.

Whether you go running in the morning, afternoon, evening — or even at all — ultimately comes down to personal preference.

Choosing the time that best suits your individual needs is key to establishing and maintaining a consistent schedule.