Sleeping in a prone position may boost seizures, death in epilepsy patients.

A recent study by the University of Chicago reviewing over 250 cases of sudden unexplained death in epilepsy (SUDEP) has shown that sleeping on chest doubles the risk of sudden death in epilepsy patients. The rates are higher especially in people younger than 40.
Among 253 instances of SUDEP in which body position was documented, nearly three-quarters of the victims -- 73.3% (95% CI 65.7%-80.9%) -- were found in a prone position. In addition, the prone position was reported in all 11 cases of video-EEG-monitored SUDEP.

The apparent risk associated with prone sleeping had been noted previously in smaller case studies, but not in one this large.
Epileptic disruption in autonomic nerve function is the presumed foundation of SUDEP, but whether that manifests primarily as cardiac arrest or respiratory failure is still debated. Researchers have drawn parallels with sudden infant death syndrome (SIDS), including the possibility that they are related conditions: SUDEP occurs disproportionately in patients during sleep, and victims are often found in a prone position, the same as in SIDS. But just as SIDS can still strike infants sleeping on their backs in line with current recommendations, SUDEP can occur in any epilepsy patient at any time: an indication that the etiology of SUDEP is complex and perhaps different from one patient to the next.

While this event is rare, people with epilepsy should not sleep in a prone position (face down). Patients should have a partner remind them at bedtime or use special devices to prevent an episode.
The study published in 21st Jan edition of Journal Neurology.