What type of sleep disorder may leave a person feeling unrefreshed upon waking?

Sleep apnea is a condition characterized by repeated interruptions in breathing during sleep, leading to fragmented sleep and a significant decrease in the quality of rest. Because individuals with sleep apnea often wake multiple times throughout the night, they fail to reach and maintain the deeper stages of sleep that are crucial for feeling refreshed and rested. This disruption in sleep architecture can leave a person feeling tired, lethargic, and unrefreshed despite potentially spending a sufficient amount of time in bed.

In contrast, REM sleep behavior disorder involves the abnormal acting out of dreams during the REM stage of sleep but primarily affects the quality of the REM phase rather than all sleep stages. Chronic insomnia refers to difficulty falling or staying asleep but does not solely determine freshness upon waking, as some individuals with insomnia might still achieve some restorative sleep. Parasomnia encompasses a variety of sleep disorders, including sleepwalking and night terrors, which may also affect sleep quality but are distinct from the recurring breathing issues seen in sleep apnea.