Simply put, sleep efficiency is the ratio taken from the time you spent lying in bed with the actual time you are sleeping till the moment you wake up the following day. There are a lot of debates regarding what is the best sleep efficiency, and tests have been used to check the correlation between sleep efficiency and the quality of sleep a person is getting. If a person spends 10 hours in bed but sleeps only for 4 hours, then his sleep efficiency is only 40 per cent. Likewise, if someone lies in bed for 8 hours and sleeps a total of 8 hours too, then it’s a perfect 100 per cent sleep efficiency.
Measuring sleep efficiency is usually done in a sleep laboratory in order to get the ratio properly. All aspects about sleep including slight awakening during sleep and how soon you get back asleep, as well as all other aspects are considered and measured to get accurate results. This is fairly hard to do by yourself since relying on your clock will only give you the time you lay down and the time you wake up. You cannot accurately measure the time you were awakened mid-sleep.
Clinical Use of Sleep Efficiency Ratings
More than just knowing how well you sleep every night, determining your sleep efficiency ratio will enable you and the doctor to diagnose any sleep disorders so that further probing could be done in order to determine the underlying causes of these disorders.
Sleep efficiency that is greater than 80 per cent is regarded as the normal value. With this amount of sleep, one will usually feel refreshed and energized in the morning. It is considered as the optimum sleep efficiency to go on with your daily activities without the risk of draining the energy out in the middle of the day. This is the ratio that everyone should aim for in order to get the best quality of sleep possible.
Sleep efficiency of less than 80 per cent, on the other hand, is a diagnostic sign that the patient is suffering from sleep disorders like insomnia and other related cases where sleep is being hampered by the inability of the body to fall into a deep sleep. In most cases, people with insomnia will have a hard time sleeping at night, and when they finally do, they often wake up shortly and then have difficulty with going back to sleep again. This significantly reduces their sleep efficiency since there will be more waking hours in-between sleep times thereby largely affecting the quality of sleep. The body’s cortisol levels play a major role in insomnia cases as insomniacs tend to have high cortisol levels at night when naturally these levels should be way down whenever we are nearing bedtime.
Sleep efficiency greater than 95 per cent, although it sounds good, is also an indication of another sleep disorder. People with sleep efficiencies higher than 95 per cent might be or prone to suffering narcolepsy or idiopathic hypersomnia. These are cases when the brain signals the glands to release excess melatonin. Melatonin is the hormone responsible in inducing sleep and giving that sleepy feeling to an individual. In narcolepsy cases, a patient has the tendency to fall asleep in a blink of an eye even though he is fairly active prior to the incident. This is particularly risky if one is driving, operating heavy equipment, or if working above ground.
Sleep efficiency ratios are not in any way final and fixed. You have the power to change your sleep efficiency ratio by changing your life style in general. The body quickly adapts to changes. So if you instill some good sleeping habits, you might be able to correct any improper sleep efficiency thereby increasing the total amount of sleep and also promoting good-quality sleeping time.