Upper abdominal pain located just below the breastbone that wakes up during the sleep is characteristic for peptic ulcer located at the first part of the small intestines, a duodenum.
You may experience abdominal bloating, nausea, retching, and early satiety.
It is a damaged lining of duodenum, as a result of Helicobacter pylori infection, using nonsteroidal anti-inflammatory drugs such as aspirin and ibuprofen, and the use of cigarettes and alcohol.

Duodenal ulcer is symptomatic before meals or 2 to 4 hours after the meal, when one is hungry, and is eased with food or acid
suppressing meds.
Having citrus juice, coffee, or aspirin trriger the pain from the duodenal ulcer.
About fifty percent of patients with duodenal ulcers awake during the night with pain, usually between midnight and three a.m.

You'll need to get tested for Helicobacter pylori infection (its treatment with antibiotics and acid suppressing drugs will help in healing the ulcer), and endoscopy!

Best wishes!