Exercising daily could stop you having nightmares, new study suggests

A run a day might help keep the boogeyman away. 

According to a new study, exercising daily could reduce the amount of time you spend dreaming each night.

Researchers from the University of Texas found that when people got at least 60 minutes of physical activity during the day, they slept better at night. 

Also, exercising reduced the amount of time people spent in the period of sleep in which dreams take place, called rapid eye movement, or (REM) sleep.

This is also the period when most people have nightmares, according to Johns Hopkins. 

This is consistent with recommendations doctors already make for reducing nightmares. 'Regular exercise, yoga and meditation may also help reduce stress and improve sleep quality,' and in turn reduce chronic nightmares, according to Stanford sleep scientists.  

Nightmares most often occur during the REM stage of sleep

The study was published in early March in the journal of Scientific Reports by psychologists from The University of Texas. 

The type of physical activity ranged from intense workouts like running and cycling to low-intensity workouts like walking or doing chores. 

Any activities that raised participants' heart rates counted towards daily exercise goals. 

Previous studies have shown that exercising can lead to improvements in sleep quality and reduce the amount of time spent in REM sleep. 

The scientists asked the 82 participants to wear Fitbits in order to capture details about sleep quality and exercise duration over a six month period. 

Using data about heart rate and bodily movement, they determined when the participants were cycling through different stages of sleep each night and how much exercise they were getting each day.

Each stage of sleep is characterized by physiological changes in heart rate and brain waves.  Here, the researchers tracked the participants' heart rate to determine when they entered different sleep stages. 

Generally speaking, heart rate slows during the early stages of sleep, but it picks up into a quicker rhythm during the time you're in REM.

Each night, your body cycles through five different stages of sleep, starting off light and getting progressively deeper. The final stage of sleep, REM, is when dreaming occurs. 

Each stage is characterized by physiological changes in heart rate and brain waves, which scientists can measure.  

There are five different sleep stages, but they can also be broken into two categories - REM sleep and non REM sleep. Participants who exercised got less REM sleep

The researchers found that on days where participants exercised, they spent less time in REM sleep, but more time in the deep sleep stages that take place before REM. 

It is thought that this deep sleep stage is when the body most recharges from the day. 'This is the stage when the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system,' according to the NIH. 

This could be why participants reported being more satisfied with their sleep quality on a night after exercise. Participants reported feeling more energetic and less stressed and sad in the morning after an exercise session.

The use of the Fitbit allowed the researchers to observe the participants in their natural environment instead of in a lab over a long period of time. 

The scientists used the heart rate tracking feature of Fitbit's to determine the participants activity level

Normally, when psychologists study sleep patterns, participants have to stay the night under observation in a lab, which can be stressful and interrupt sleep quality.

Also, because of the costs associated with this set up, most studies of this kind last only a few nights. 

'You can learn a lot from lab studies, but obviously, there are limitations to studying the sleep patterns of individual participants in just one night,' study co-author Benjamin Baird said. 

This has potential applications in future studies, David Schnyer, another co-author, said.

'The world is your oyster now. You can use this device to study all manner of different sleep architecture data related to lifestyle — related to mood and mood disorders — in the field, not in a lab, that people might have thought was not possible previously,' he said.