The mechanism of dead-in-bed syndrome and other sudden unexplained nocturnal deaths.

The mechanism of dead-in-bed syndrome (DBS), a rare but devastating condition that mainly affects young type 1 diabetes patients, remains mysterious. A new theory is proposed to explain this syndrome. This theory suggests that repeated episodes of hypoglycaemia-induced adaptation in orexin-A neurons cause (i) defective awakening and (ii) hypotonia of upper airway muscles during sleep. Consequently, due to the combined effect of these factors, long-term exposure of intermittent hypoxia occurs, leading to a combination of factors - such as depression of ventilation, increase in sympathetic tone, fluctuations in intrathoracic pressure and cardiac arrhythmias - these in conjunction with an underlying cardiovascular pathology (genetically inherited or acquired) cause cardio-respiratory failure and thus sudden death during sleep. This mechanism can be generalized to explain other cases of sudden unexplained nocturnal deaths including sudden infant deaths (SIDs).