http://www.mayoclinic.org/healthy-lifestyle/adult-health/expert-answers/how-many-hours-of-sleep-are-enough/faq-20057898

How did it work? Why did people do it? And how could something that was once so completely normal, have been forgotten so completely? One of the most common treatments is continuous positive airway pressure (CPAP). This therapy employs a small bedside machine that pumps air through a flexible hose to a mask worn over your nose and mouth. It took some time for their sleep to regulate but by the fourth week a distinct two-phase sleep pattern emerged. They slept first for four hours, then woke for one to three hours before falling into a second four-hour sleep. This finding suggests bi-phasic sleep is a natural process with a biological basis. Pros and cons The practice even made it into ballads, such as "Old Robin of Portingale. "… And at the wakening of your first sleepe, You shall have a hot drink made, And at the wakening of your next sleepe, Your sorrows will have a slake…" Around a third of the population have trouble sleeping, including difficulties maintaining sleep throughout the night. While nighttime awakenings are distressing for most sufferers, there is some evidence from our recent past that suggests this period of wakefulness occurring between two separate sleep periods was the norm.As you get used to a biphasic sleep schedule, be diligent about maintaining consistent bed and wake times. Not only will following a regular sleep schedule make it easier for you to adjust, but going to sleep and waking up at inconsistent times is associated with poor long-term health outcomes, like a greater risk Those of a philosophical disposition, meanwhile, might use the watch as a peaceful moment to ruminate on life and ponder new ideas. In the late 18th Century, a London tradesman even invented a special device for remembering all your most searing nightly insights – a "nocturnal remembrancer", which consisted of an enclosed pad of parchment with a horizontal opening that could be used as a writing guide. For husbands and wives who managed to navigate the logistics of sharing a bed with others, it was also a convenient interval for physical intimacy – if they'd had a long day of manual labour, the first sleep took the edge off their exhaustion and the period afterwards was thought to be an excellent time to conceive copious numbers of children. Split-shift schedules that maintain adequate sleep time per 24 hours may be beneficial for sleep, performance, and safety. A number of recent studies have found split sleep provides comparable benefits for performance to one big sleep if the total sleep time per 24 hours was maintained (at around seven to eight hours total sleep time per 24 hours).

When Ekirch expanded his search to include online databases of other written records, it soon became clear the phenomenon was more widespread and normalised than he had ever imagined.Both short and long sleep durations are associated with a number of health concerns and chronic diseases: Biphasic sleep describes a pattern of sleep in which a person sleeps in two segments, or phases, per day Oversleeping can occur when you try to make up for your “sleep debt.” For example, you may have to stay up late several nights in a row to complete a big project and therefore become sleep deprived. Then, on the weekend you might make up the sleep debt by sleeping longer than normal. As Jane later explained to a courtroom, her mother had evidently been expecting the visitors. She went with them freely – but first whispered to her daughter to "lye still, and shee would come againe in the morning". Perhaps Mrs Rowth had some nocturnal task to complete. Or maybe she was in trouble, and knew that leaving the house was a risk.

Stage 2 (NREM). In stage 2, which is called N2, your body temperature drops while your heart rate and breathing continue to slow. Stage 2 lasts for about 25 minutes in your first sleep cycle and gets longer with each additional cycle. Healthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references. You can learn more about how we ensure our content is accurate and current by reading our editorial policy. Starting 30 to 60 minutes before you sleep or take a nap, reduce your exposure to artificial light. Artificial light includes the light from phones, televisions, computers, and tablets. It also helps to dim lamps and overhead lights. We only cite reputable sources when researching our guides and articles. These include peer-reviewed journals, government reports, academic and medical associations, and interviews with credentialed medical experts and practitioners. Biphasic sleeping is practiced by a variety of people across cultures. For example, people who enjoy siestas are considered biphasic sleepers. Some people adopt a biphasic sleep schedule to maximize their productivity. Additionally, many animals are biphasic sleepers, including birds, insects, and mammals

Your Sleep Foundation Score™ has been calculated!

In her testimony, Jane describes how just before the men arrived at their home, she and her mother had arisen from their first sleep of the evening. There was no further explanation – the interrupted sleep was just stated matter-of-factly, as if it were entirely unremarkable. "She referred to it as though it was utterly normal," says Ekirch. Taking care of yourself during waking hours will help your sleep. Think about the things you consume. Caffeine may wind you up if consumed too close to bedtime. Alcohol can make you sleepy, but it actually makes your quality of sleep worse. Herbal tea or warm milk are better substitutes. Exercise is good for your body, but doing it right before you go to bed may disrupt your sleep. 5. Keep a sleep diary