1 Onset of sleep from time the lights were turned off; this is called  sleep onset latency  and normally is less than 20 minutes. ( 2 Note that determining sleep and awake is based solely on the EEG. Patients sometimes feel they were awake when the EEG shows they were sleeping.
The direct cost margin is calculated by taking the difference between the revenue generated by the sale of goods or services and the sum of all direct costs associated with the production of those goods, divided by the total revenue.
Gross Profit Margin: The gross profit margin equation is typically used to determine the profit margin of a singular product or service, not of an organization as a whole. To determine the gross profit margin, a business looks at the retail price of its product and subtracts the cost of materials and labor used to produce it. It then divides that by the retail price. For example, if you sell a product for $25, and it costs $20 to make, the gross profit margin is 20% ($5 divided by $25). Net Profit Margin: This is often the equation used to determine an entire organizationâs profit margin. Net profit margin is calculated by taking the companyâs total sales for a given time period, subtracting total expenses and then dividing that figure by total revenue. For example, letâs say your company generates $10 million in sales and has operating expenses of $5 million.