Generally, newborns sleep about 8 to 9 hours in the daytime and about 8 hours at night. Most babies do not begin sleeping through the night (6 to 8 hours).
The athletes needed 8.3 (0.9) hours of sleep to feel rested, their average sleep duration was 6.7 (0.8) hours, and they had a sleep deficit index of 96.0 (60.6.
The supine position may be disadvantageous for fetal wellbeing and in compromised pregnancies may be a sufficient stressor to contribute to fetal demise.