Polysomnography is used to diagnose, or rule out, many types of sleep disorders including narcolepsy, idiopathic hypersomnia, periodic limb movement disorder (PLMD), REM behavior disorder, parasomnias, and sleep apnea.
Calculating Due Date: Estimated Due Date. Based on the last menstrual period, the estimated due date is 40 weeks from the first day of the period. This is just an estimate since only about 5% of babies are born on their estimated due date.
Calculating exact age from date of birth (in years, month and days) To calculate an exact age in years, months and days, write three DATEDIF functions with the following units in the last argument: Y - to calculate the number of complete years. YM - to get the difference between the months, ignoring years.