"profound sleep" is correct and usable in written English.
You can use it to describe a deep and restorative sleep, often a metaphorical one. Example: After a long day's work, I was overcome with a profound sleep.
They fell into a profound sleep.
One form includes vivid hallucinations on awaking or falling asleep, temporary but profound sleep paralysis on awakening that does not affect breathing, and sudden, brief loss of muscle power in the limbs and trunk during emotional moments such as laughter (cataplexy).
La Morgia and her colleagues, aware of the profound sleep problems often seen in Alzheimer's, wondered whether the cells may stop doing their job as the disease progresses.
From the operating table you can only fall a few feet at the most or gently pass from profound sleep into oblivion, never knowing the difference.
The stern voice of his father at last checked the wild torrent of words; they took him to bed, and a profound sleep of twelve hours restored him to his normal state".
In 1811 she travelled from Rome to Naples, splitting the journey in half with a stop after 60 miles (97 km), and later ascended again from Rome to a height of 12,000 feet (3,660 m) where she claimed that she fell into a profound sleep for a while before landing at Tagliacozzo.
That's just not even worth thinking about, is it?" Blogs were written: "In some deep, profound, sleep-deprived way, each of us is CBeebies.
I was sleeping 8 to 10 hours a night, but I still had a profound delta sleep deficit.
Cocaine-use disorders are associated with profound abnormalities in sleep and sleep architecture.
Our data demonstrate that drug-free patients with chronic undifferentiated type schizophrenia suffer from profound disturbances in sleep continuity and sleep architecture.
Chronic fatigue syndrome causes a host of debilitating symptoms: profound exhaustion, disordered sleep, muscle and joint pain and severe cognitive problems, among others.
