Your Sleep Need? Figure It Out Yourself

You’ve heard the advice to get 8 hours of sleep a night? Now they’re saying that 7 hours is the optimal amount of sleep–which may not be very cheering for most people with insomnia. Still our nights do not measure up.

If you have persistent insomnia, and if you fall short of the recommended 7 or 8 hours, it’s natural to wonder if you’re getting enough sleep. Here’s how to get a good sense of how much sleep you really need.

calculate your sleep need by keeping track of the hours you sleep on vacationYou’ve heard the advice to get 8 hours of sleep a night? Now they’re saying that 7 hours is the optimal amount of sleep–which may not be very cheering for most people with insomnia. Still our nights do not measure up.

As if that weren’t bad enough, the web is glutted with articles showing that short sleepers are vulnerable to a host of ailments: depression, heart disease, obesity, diabetes, dementia. Yikes! It’s a wonder any of us live past 65.

If you have persistent insomnia, and if you fall short of the recommended 7 or 8 hours, it’s natural to wonder if you’re getting enough sleep.

How Much Sleep Is Enough?

Sleep need—or sleep ability—varies a lot from one person to the next. Some people feel refreshed after 5 hours while others need 9. In normal sleepers, the duration of sleep is fairly consistent from one night to the next, so it’s easy to make inferences about sleep need. A person who under favorable conditions normally falls asleep at 11 and wakes up at 6 needs an average of 7 hours’ sleep a night.

But the sleep of people with insomnia is much more variable. Insomniacs are 60 percent more likely than good sleepers to sleep poorly on any given night. After a slew of bad nights, it feels heavenly to pop off a solid 8 hours. You wake up feeling rested and ready for the day—and this might lead you to infer that you need 8 hours a night to function at your peak.

But it’s a mistake to assume that the sleep you get on a night of recovery sleep is equivalent to the amount of sleep you need every night. It’s also wrong to assume that the 4 hours you more often get will suffice. The truth lies somewhere in between.

Track Your Sleep over Time

To find the amount of sleep you need for optimal functioning, keep track of the hours you sleep for a week or two and then take the average of that. This is probably closer to your daily sleep need.

But . . . this figure may be off the mark for people with persistent insomnia. Stress can interfere with sleep and make it hard to get an accurate read on sleep need. You may be slightly but chronically low in the tank.

A Better Way to Calculate Sleep Need

Eve Van Cauter, director of the Sleep, Metabolism and Health Center at the University of Chicago, suggested a better way to figure out sleep need or capacity in last week’s USA Today. Here it is:

Wait until you’re on vacation and free of the stressors connected to the daily grind. Once you’re away, go to bed at your usual time but do not set an alarm clock. The first few days you may sleep longer than normal to make up for the sleep debt you’ve accumulated at home.

Then, once your sleep stabilizes, start keeping track of how long you sleep. This, plus or minus 15 minutes, Van Cauter says, is as good a way as there is to get a handle on your daily sleep need.

How Much Sleep Is Enough?

Getting 8 hours’ sleep a night is as healthful as eating 9 servings of fruit and vegetables and getting daily exercise—or so we’re told. In truth there’s no way to determine how much sleep any one of us really needs.

But the 8-hour recommendation is based on something, which is why we hear it so much. For those concerned about getting too little sleep, here are 3 ways to find out how much you’re actually getting.

Regarding sleep need, sleep quality may matter more than sleep durationGetting 8 hours’ sleep a night is as healthful as eating 9 servings of fruit and vegetables and getting daily exercise—or so we’re told. In truth there’s no way to determine how much sleep any one of us really needs.

But the 8-hour recommendation is based on something, which is why we hear it so much. Recent studies show “a strong association between nightly sleep duration and mortality risk,” Michael Grandner and colleagues say in a paper on sleep duration and health. Overall, people who report sleeping 7-8 hours a night live longer than people who report sleeping 9-10 hours and those who report sleeping 6 hours or less.

The same is true of the relationship between sleep duration and cardiovascular disease (and related conditions such as hypertension and diabetes). Short and long sleepers tend to be more vulnerable to these ailments than people who sleep 7-8 hours a night. Of interest to those of us with insomnia, short sleepers (who sleep 6 hours a night or less) with poor quality sleep have a much higher risk of developing cardiovascular disease.

Counting the Hours

If you’re concerned you’re not sleeping enough, consider the possibility that you may be sleeping more than you think. About 5 percent of insomniacs have “paradoxical insomnia.” Usually pretty energetic during the day, they feel like they sleep just a few hours a night. Yet polysomnography (PSG)—the test performed in a sleep lab—shows 7 or 8 hours of sleep-like activity going on in most of the brain. (I’ll explain this phenomenon in another blog.)

Many of us perceive the lightest sleep stage as waking. Up to 50 percent of the time, the brainwave patterns of insomniacs who undergo sleep studies look exactly the same as those of normal sleepers. So our perception of sleep does not always jibe with sleep as measured by PSG. And the while PSG cannot assess sleep quality, its assessment of sleep duration is important. People whose polysomnograms show they get considerably less than 7-8 hours’ sleep a night are the ones most vulnerable to cardiovascular disease and early death.

Objective Sleep Measures

Here are 3 ways to find out how much you sleep.

  • A sleep study. There are lots of downsides to going this route. It requires a doctor’s prescription, costs a lot, and is just a one-shot deal. Insomniacs’ sleep tends to vary a lot from night to night, and a sleep study is not going to provide information about your sleep duration over time, which is really what you want.
  • Actigraphy. This involves wearing a wristwatch-type device to bed for several nights. The actigraph assesses your sleep-wake patterns based on bodily movement. It’s fairly reliable most of the time. It also requires a doctor’s prescription.
  • Sleep-monitoring devices available without prescription. I’ve written about the Beddit, and a Google search will acquaint you with several others. These devices are relatively inexpensive, but none of them have been tested on insomniacs. They may not be sensitive enough to assess the nuances of insomniac sleep. (Coincidentally, just a few days after this blog post went out, Dr. Christopher Winter, who tested several sleep tracking devices on himself, posted a review of his findings in Huffington Post. It’s definitely worth reading if you’re considering buying one for yourself.)

Me personally? I know I’m a short sleeper but I’m not so concerned with racking up the hours. Health and longevity depend on several factors. Regarding sleep, I’m convinced that quality, and not quantity, matters more.

If you’ve undergone a sleep study or tried monitoring your sleep in some other way, what did you find out? Were you sleeping more—or less—than you thought?