What hormone, produced in the hypothalamus, is associated with arousal and the loss of which can lead to narcolepsy?

The hormone associated with arousal that is produced in the hypothalamus is orexin. Orexin plays a crucial role in regulating wakefulness and energy metabolism. It is involved in maintaining a stable level of arousal and alertness. A deficiency in orexin is linked to narcolepsy, a sleep disorder characterized by excessive daytime sleepiness and sudden sleep attacks. In individuals with narcolepsy, the loss of orexin-producing neurons leads to the inability to maintain wakefulness, highlighting the importance of this hormone in the sleep-wake regulation.

In contrast, oxytocin is related to social bonding and reproductive behaviors, adrenaline is involved in the body's fight-or-flight response, and endorphins act as natural painkillers and mood enhancers. These hormones serve different functions and do not have the same direct association with arousal and narcolepsy as orexin does.