Feeling nauseous in the morning can be caused by various factors. Common reasons include acid reflux (where stomach acid escapes into the esophagus during sleep), low blood sugar due to long periods without eating, dehydration especially after alcohol consumption, anxiety or stress affecting the gut- brain connection, and poor or irregular sleep disrupting the body's rhythms. Other causes might be sinus congestion, inner ear problems causing dizziness, or even more serious conditions like gastroparesis. Specifically:

• Acid reflux can worsen overnight because lying flat facilitates stomach acid moving up, causing nausea.
• Low blood sugar after fasting overnight can cause weakness, dizziness, and nausea.
• Dehydration from not drinking fluids at night or after alcohol leads to nausea.
• Anxiety or stress can activate gut nervous pathways causing nausea.
• Poor sleep or sleep interruption changes body hormone balances and can trigger nausea.
• Postnasal drip or sinus issues can irritate the stomach upon waking.

Addressing these causes often includes eating a light snack if blood sugar is low, improving sleep hygiene, staying hydrated, managing stress, and avoiding eating close to bedtime to reduce acid reflux.