"Sleep deprivation can lead to immunologic dysfunction," noted Dr. Jordan Josephson, a sleep apnea specialist at Lenox Hill Hospital in New York City.

"The unique immunologic status of pregnant women might alter disease presentation and progression," wrote Dr. Emma Akerlund of Doctors Without Borders and two colleagues.

Untreated, it can result in prolonged sleep disturbance, substance abuse, suicidal thoughts and behaviors, immunologic abnormalities, and an increased risk of heart disease and cancer.