Hello and hope you are doing well.
There is more of REM sleep in your nighttime sleep study; hence the doctors have tried to rule out narcolepsy, which causes excessive sleepiness. Narcolepsy is characterized by excessive day time sleepiness, sleep paralysis, cataplexy where the person has episodes of loss of muscle function while awake, hypnogogic hallucinations and automatic behavior.
Narcolepsy is diagnosed by the sleep onset REM episodes (SOREMs), wherein the person goes into the dream phase or REM cycle soon after sleep onset. This is evident in the Multiple Sleep Latency Test (MSLT). But there are no REM episodes in your MSLT ruling out the possibility of Narcolepsy.
Hope this helped and do keep us posted.