Feeling excessively sleepy during the day is a common complaint in the modern era. Sometimes it is due to just not getting enough sleep or having very disrupted sleep (such as by sleep apnea or restless legs). It can be related to other imbalances in the brain chemistry. Narcolepsy is one very specific example of this where there are lower than normal levels of orexin/hypocretin in the brain. If a neurological cause of sleepiness is suspected, all other sleep issues need to be addressed. Then specific testing is done in a sleep laboratory (diagnostic polysomnography and multiple latency sleep testing). If we do identify a condition such as narcolepsy, sometimes lifestyle modifications can help improve sleepiness. Other times medications are needed and can require multiple careful adjustments to optimize the timing and duration of wakefulness while minimizing side effects.