New study shows parents are sleep deprived in the first 3 months after baby is born Video

Now Playing: Sleep Series: Gadgets to help with sleep

Now Playing: Wild weather slams the country from coast to coast

Now Playing: No charges for officers in shooting death of unarmed black man, Stephon Clark

Now Playing: Investigators find cockpit voice recorder for crashed cargo jet

Now Playing: Northeast slammed by 2nd snowstorm

Now Playing: Moose and its calf seen in Washington backyard

Now Playing: Police shootout near elementary school

Now Playing: Father of hit-and-run victim speaks out

Now Playing: Video shows rescue of girl after plane crashed into building

Now Playing: Historic SpaceX test flight bound for International Space Station

Now Playing: The defense presents an 11th hour witness: Part 10

Now Playing: Liam McAtasney found guilty of murdering childhood friend Sarah Stern: Part 11

Now Playing: Liam McAtasney, Sarah Stern’s childhood friend, goes to trial for her murder: Part 9

Now Playing: Two friends of Sarah Stern are arrested in her disappearance: Part 8

Now Playing: Liam McAtasney’s roommate admits to helping dump Sarah Stern’s body: Part 7

Now Playing: Filmmaker who knew Sarah Stern’s childhood friend breaks case wide open: Part 6

Now Playing: Police learn Sarah Stern put away over $25K shortly before disappearance: Part 5

Now Playing: No leads three days into search for Sarah Stern: Part 4

Now Playing: Community comes together to search for Sarah Stern: Part 3

Now Playing: Sarah Stern case investigators question Sarah’s friends: Part 2