“The predominant theory regarding the pathophysiology of primary insomnia centers around a state of hyperarousal, manifested in hyperactivity of corticotropin-releasing factor (CRF). Initial insomnia may occur as a result of some psychosocial stressor or other precipitating factor that increases arousal of the hypothalamic–pituitary–adrenal axis. A study of young patients with insomnia, compared to age- and BMI-matched healthy controls, revealed higher 24-hour mean secretions of adrenocorticotropic hormone and cortisol.”
Note that Obstructive sleep apnea is also associated with insulin resistance.
The hormone that causes weight gain in sleep deprivation is cortisol, not insulin.
This shows again that Obesity is a hormonal imbalance, not a caloric one since sleep deprivation neither carries calories nor has carbohydrates with it.
Further Reading
Hargens TA, Kaleth AS, Edwards ES, Butner KL. Association between sleep disorders, obesity, and exercise: a review. Nature and Science of Sleep. 2013;5:27-35. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3630986/