The study is a case-controlled observational trial. Sixty patients will be divided into 2 groups (good or poor sleepers) depending on their first postoperative night Bispectral index data. Firstly, this study aims to characterise the gut and lung microbiota in patients with lung cancer treated with surgery. Secondly, it aims to evaluate microbiota and its influence on plasma kynurenine.

The study is a case-controlled observational trial. Sixty patients will be divided into 2 groups (good or poor sleepers) depending on their first postoperative night Bispectral index data. Firstly, this study aims to characterise the gut and lung microbiota in patients with lung cancer treated with surgery. Secondly, it aims to evaluate microbiota and its influence on plasma kynurenine.

Inclusion Criteria:

• 1. ethnic Chinese;
• 2. age, 18 to 75 years old;
• 3. American Society of Anaesthesiologists (ASA) physical status I or II;
• 4. required VATS for lung surgery and one lung ventilation .

Exclusion Criteria:

• Cognitive difficulties
• Partial or complete gastrectomy
• Previous esophageal surgery
• Previous treated by radiotherapy or surgery
• Inability to conform to the study's requirements
• body mass index exceeding 30 kg/m2
• Deprivation of a right to decide by an administrative or juridical entity
• Ongoing participation or participation in another study <1 month ago
• preoperative Pittsburgh Sleep Quality Index global scores higher than 6
• recent (< 3 months prior) use of antibiotics, probiotics, prebiotics, symbiotics, hormonal medication, laxatives, proton pump inhibitors, insulin sensitizers or traditional Chinese medicine

male

The study is a case-controlled observational trial. Sixty patients will be divided into 2 groups (good or poor sleepers) depending on their first postoperative night Bispectral index data.