Any sympton that is unusual for you can indicate stress.
Tense muscles, sore neck, shoulders, & back
A person under stress may be so tense that they experience muscle cramps. Tight neck, shoulder, and upper back muscles may lead to headace. Other tight muscles may cause backache.
Trouble falling asleep, staying asleep, or early waking. Tense muscles and increased heart and breathing rate brought on by stress can cause insomnia.
This is a symptom of stress unless the fatigue is brought on by physical exertion.
Boredom, depression, listlessness
A person who is constantly in any of these states and does not "snap out of it" is under stress, which saps them of their energy.
Drinking too much
Drinking to escape problems creates more problems. Danger signals are: needing a drink, drinking every day or at a set hour, drinking from the bottle, drinking first thing in the morning, blacking out.
Eating too much or too little
Compulsive eating can put added strain on the heart, kidneys, and arteries, and can create self-disgust (a major stressor). Eating too little can signify withdrawal and depression.
Diarrhea, cramps, gas, constipation
Symptoms of digestive distress can come from spoiled food or viral infection, but persistent trouble can indicate stress. The blood is drawn away from the digestive system.
Palpitations (heart skip)
The stress alarm increases the rate of heartbeat, causing a feeling of palpitations or heart skip. This can result in a destructive cycle of fear--stress alarm--palpitations--fear of palpitations--alarm.
Unfounded fears, such as fear of enclosed places, heights, etc. could be a sign of stress caused by hidden emotional conflicts.