Do you feel well-rested? Are you already looking forward to the next coffee? Do you feel exhausted? Do you wish you had more energy? More focus? All of these questions lead to one broader question: are you getting enough sleep?

Before we can answer that, first we should investigate what a normal amount of sleep actually is. The availability of artificial light since the 1840s has allowed us to be active beyond our natural limits, taking away from the time we might be naturally asleep. The validity of this idea can be examined by looking at “experiments of nature,” societies that have no electricity to provide the artificial light that extends the useful day, societies which exist as hunter-gatherers.

In a study by Jerry Siegel, Ph.D., professor of psychiatry at UCLA, three hunter-gatherer societies were studied using activity monitors (a validated medical version of FitBit or Jawbone) with light meters which found that these disparate societies show similar sleep parameters. They do not sleep more than modern humans, with average durations of 5.7 to 7.1 hours, they go to sleep three hours after sunset and awake before sunrise, with ambient and body temperature driving these times. Little napping was seen.

In more agriculturally active but still pre-industrial societies, evidence points to “double sleeping” with bedtimes at sunset and frequent reports of waking after midnight, to be active by candlelight, and returning to sleep between 3 a.m. and 5-6 a.m. Although the total sleep time is unknown it looks as if it was the same seven hours but in two doses.

But what about the rest of us? National Sleep Foundation guidelines suggest we need seven-to-eight hours in our adult years and statistically that’s true, and therefore most likely true for you, too. But, for the individual contributing to the pool of data which gave rise to that average number, it may not be. So how do we know how much sleep we need? The clinical answer is “the amount of sleep needed to prevent sleepiness and to allow one to perform adequately in the day without limitations.” A good example is sustained attention which becomes more difficult to maintain, sometimes, and more often than we would wish, resulting in sleep-related accidents (driving is the best example of the need for sustained attention). This amount of sleep can be easily judged, for example on vacation when, after a period of catch-up sleep, we fall into our natural routine and for most this will be seven to eight hours. But this definition is perhaps flawed since “performance” may be more subtly affected than just “performing adequately without limitation in the day.” More subtle effects of lack of sufficient sleep are becoming more evident.

For example, there is a potential for an increase in arguments at work because of labile emotions and reduced self-control. You may see an increase in hunger due to well-understood changes in the appetite hormones leptin and ghrelin. The former is the satiety hormone which is reduced by 20 percent after sleep restriction, and the latter the appetite hormone levels of which increase by 20 percent. There is also the chance for altered judgment which has produced changes in the outcome of court proceedings (sentences are more severe in the afternoon, a time when prior lack of sleep increases sleepiness) and a lack of leadership skills in soldiers subject to sleep restriction.

In addition to that, a change in moral awareness made evident by a study of Google searches on the day after daylight saving time when people search less commonly for words with a moral content.

And as if that weren’t enough, there are even documented physical consequences of lack of sleep. There is an increased susceptibility to infections such as the common cold, to having poorer looking skin, and to higher blood pressure.

So, are you getting enough sleep? It’s clearly important, and so it goes that it’s also important that we pay as much attention to our sleep as we pay to our diet and our exercise. Shortchanging yourself on sleep now only short-changes you in other areas later. If you’re having trouble sleeping (or just having trouble prioritizing), give meditation a try. It might be just what you need for the right amount of sweet dreams.

The author of this post is an editorial contributor to Headspace. These are their views, experiences and results and theirs alone. This contributor was paid for their writing.