Short Duration Sleep and Sleep Restriction

Spending Less Time In Bed Reflects Different Conditions

You hardly get enough time in bed at night. Once you have met your work or family obligations, you just need a little time to relax. By the time you make it to bed, you are there only a short period before the alarm clock drags you back to consciousness to start another day. You are lucky if you get 5 hours in bed per night.

Perhaps the scenario is different. Alternatively, you are the type of person who only needs a good 4 hours of sleep before you feel completely refreshed and ready to tackle another day.

Are these two distinct scenarios best described as insomnia? If not, what is it called when you choose to limit your time in bed?

To better understand these scenarios, let’s review an excerpt from UpToDate -- a trusted electronic medical reference used by health care providers and patients alike. Then, read on farther below for additional information about what all of this may mean for you.

"Insomnia is frequently confused with short sleep requirement and sleep deprivation:
  • Sleeping for only a short period of time is common among people who have insomnia. However, some people normally require little sleep and can function without difficulty after sleeping for only a few hours. People who sleep less but have no residual daytime sleepiness are called short sleepers and do not have a sleep problem. In addition, you may need less sleep as you get older. Needing less sleep does not necessarily mean that you have insomnia unless you also have daytime symptoms (daytime sleepiness).
  • People who are sleep deprived, as well as those with insomnia, sleep for a short time and have difficulty functioning during the daytime. However, people who are sleep deprived will fall asleep quickly if given the opportunity. Chronic loss of sleep, caused by spending fewer than 8 hours in bed on most nights, is probably the most common cause of sleepiness. About one-third of adults suffer with chronic loss of sleep effects. However, not getting enough sleep is much different from insomnia, which is the inability to sleep given the chance to sleep."

Insomnia is best defined as difficulty falling or staying asleep or sleep that is not restorative. If you can get by with less sleep or you do not spend enough time in bed, then it is not insomnia.

Everyone’s sleep needs vary and the amount of sleep that we need changes over our lifetimes. Your genes determine the amount of sleep that you need.

For some people, 6 hours may be enough while just as many people may need 10 hours. The average works out to be about 8 hours, which is what we are commonly told is the amount of sleep that the average person needs. Therefore, if you wake up refreshed after a short period of sleep, you are said to be a "short sleeper."

This may not be a static need, however, as it changes as we develop. The sleep of children changes the most dramatically. Infants may seem to sleep throughout the day and night, but they often awaken to feed. Therefore, it is said that their sleep is not consolidated into one long nighttime period. This happens later in childhood, and it is hailed as a major developmental milestone by parents (because it allows the whole family to sleep through the night).

Moreover, as we age, we also may find our sleep requirement diminishes. It might be suggested that we need less sleep as we get older. Perhaps just as likely is that we are unable to sleep as well. The mechanisms of sustained sleep may degenerate.

As such, we might not be able to stay asleep as long. Just as evident, we may not be able to sustain wakefulness and naps may become part of our routines. In addition, there may be a subtle shift in when we desire to sleep, as older people are more likely to fall asleep and wake earlier (characteristic findings of advanced sleep phase syndrome).

If you are not adversely affected by short sleep duration, no matter your stage in life, you do not have insomnia. If you awaken feeling refreshed and you do not feel excessive daytime sleepinesss, this is a sign of health and not a disorder.

Conversely, some people spend fewer hours in bed than they need and they do suffer consequences. Sleep deprivation is getting less sleep than your body needs. There may be many significant consequences to your health, including physical effects, such as an increased risk of obesity and even death. The key distinction from insomnia is that in the case of sleep deprivation, given the opportunity to sleep, it comes easily.

Therefore, it is not insomnia if you do not spend the time in bed that you need to sleep or if you simply do not need that extra time to feel rested and to function at your best.

Want to learn more? See UpToDate's topic, "Insomnia," for additional in-depth medical information.

Source:

Bonnet, Michael et al. "Insomnia." UpToDate. Accessed: January 2012.

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