Stress CAN cause sleepwalking.
More Info: Though stress is not an underlying cause of sleepwalking, it can trigger episodes in those who are prone to the sleep disorder.
What Is Sleepwalking?
Somnambulism, or sleepwalking, is a condition often related to childhood, but it can occur in adults, as well. Sleepwalking is not a disease but a behavior that may relate to an underlying disorder. Like most behaviors, it has common triggers and stress is one of them. Some people get a stomachache when they feel stress, others might get an itchy skin rash and a few may sleepwalk. Controlling stress will go a long way to preventing occurrences in sleepwalkers. 
Does Stress Cause Sleepwalking?
If you are a sleepwalker, you can’t blame it all on stress. No one really knows why some people walk in their sleep. The condition tends to run in families. A child with one parent who sleepwalks is at risk for developing this behavior. If both parents sleepwalk, the risk increases. While doctors may not know exactly what causes this activity, they do know what factors tend to trigger it. 
The Physiology of Stress
The fact that estimates suggest that 75%-90% of all doctors visits are for stress related complaints and ailments demonstrates how common stress is as well as the impact that it has on overall health and well being.  The body reacts to stressful situations by releasing hormones such as adrenaline that help the body to react quickly to life-threatening situations. During a stressful situation, your body essentially enters survival mode by increasing energy levels and heart rate while shutting out those things not needed for immediately survival such as digestion, growth, and reproduction. So though stress plays an important role in the survival of the animal kingdom, chronic stress over non-life threatening things such as money problems is going to wreak havoc on the body long-term. Chronic stress can increase your risk of heart disease, diabetes, high blood pressure, digestive disorders, suppressed immune system, reproductive issues, and impaired brain function. 
Stress as a Trigger
Stress is high on the list of triggers for sleepwalking. Stress is a normal part of life, but when the feeling becomes progressive and overwhelming, the body responds. Often this means triggering an underlying condition. For example, people with eczema may have an outbreak and sleepwalkers may start roaming at night.
Controlling the Stress
Getting a handle on your stress will help, but it may not be enough. Kids usually will outgrow the problem, but adults who are experiencing sleepwalking for the first time need to get a medical evaluation to rule out an organic cause.
Sleepwalking can have some serious side effects. If stress is getting you out of bed at night, take measures to control it. Exercise is a natural stress reducer. Take a walk when you feel overwhelmed. If you can’t get a handle on the problem, see your doctor for help. 
 National Center for Biotechnology Information
Sleepwalking: Walking during Sleep; Somnambulism
 Mayo Clinic
Sleepwalking: Risk Factors
[3 ] WebMD
The Effects of Stress on Your Body
 Stanford News, Stanford University School of Medicine
Robert Sapolsky discusses physiological effects of stress
 National Library of Medicine
Stress and Anxiety: Medline Plus Medical Encyclopedia
Resource: Psych Central
The Physiological Effects of Long-Term Stress
Glossary of Terms
Physiological: characteristic of or appropriate to an organism’s healthy or normal functioning.
Somnambulism: (ie, sleepwalking) is a disorder of arousal that falls under the parasomnia group. Parasomnias are undesirable motor, verbal, or experiential events that occur during sleep. These phenomena occur as primary sleep events or secondary to systemic disease. They are categorized as those occurring in rapid eye movement (REM) sleep; those occurring during non–rapid eye movement (NREM) sleep; and miscellaneous types that do not relate to any specific sleep state.
“Primates are super smart and organized just enough to devote their free time to being miserable to each other and stressing each other out,”. . . “But if you get chronically, psychosocially stressed, you’re going to compromise your health. So, essentially, we’ve evolved to be smart enough to make ourselves sick.”
Stanford neuroscientist Robert Sapolsky