Hormonal

Five nights of sleep restriction (4 hours time in bed) impairs glucose metabolism by increasing post-prandial glucose and insulin levels, while simultaneously increasing afternoon/evening cortisol and decreasing sex hormone binding globulin (SHBG).

If you are a healthy young man, restricting your sleep to 4 hours for five nights will significantly impair your body's ability to handle glucose after meals, even if your fasting blood sugar looks normal. This is accompanied by higher stress hormones (cortisol) and lower SHBG. To mitigate this, prioritize getting adequate sleep (7-9 hours) as it is a critical lever for metabolic health, comparable to diet and exercise.