How much sleep is enough? For anyone interested in sleep, this is the most common and essential question. The truth is, when it comes to sleep duration there is no single number that is right for everyone. Sleep needs vary by individuals, and also over the course of a lifespan. We begin life with a high demand for sleep – newborns spend somewhere between 16-20 hours a day sleeping. Young children generally require 10-12 hours of sleep to meet their needs, and adolescents typically need 9 or more hours. Most healthy adults require somewhere in the range of seven to nine hours of nightly sleep to feel rested, mentally sharp and alert, with sufficient energy to meet the demands of the waking day. There are people who can function well on six hours or less of sleep, but scientists estimate this is no more than a small sliver of the general population – around 3 percent. Most of us need at least seven or more hours of sleep on a regular basis to function at and feel our best.
Sleep changes with age
With age, adults experience changes to sleep patterns that can affect sleep duration. Older adults spend less time in deep sleep and REM sleep, and more time in lighter, less restorative phases of sleep. As a result, they may sleep less at night. Our need for sleep doesn’t diminish with age, but older adults may find the need to adjust their sleep habits – such as including daytime nap – to continue to get sufficient rest.
Sleep quantity matters
For many people, getting this much sleep on a regular basis might seem unrealistic or difficult to achieve. Busy schedules, the rigorous demands of work and family life often push sleep aside. In the United States, sleep deprivation has reached epidemic levels. Estimates are that nearly a third of U.S. adults are sleeping less than seven hours a night. Chronic insufficient sleep has serious and long-term consequences for health, productivity, and relationships. Getting enough sleep on a regular basis is not only possible, but it’s also too important to ignore.
Facing a sleep debt?
The occasional night of short sleep duration is normal and to be expected. A night or two of abbreviated sleep now and then will make you feel mentally and physically fatigued, but won’t affect your health or performance over the long term. Sleep deprivation becomes a problem to health and quality of life when it becomes the rule rather than the exception. Not getting sufficient amounts of sleep creates what experts call sleep debt. Sleep debt accrues like any other kind of debt, when you don’t “pay in” what you owe – in this case, sufficient time for restful sleep.
A little sleep debt is actually a good thing. Being tired at the end of the day helps increase the need for sleep. Too much sleep debt can cause problems with daily functioning and overall health. A large sleep debt can lead to diminished mental performance, changes to appetite that lead to weight gain, difficulty in relationships.
How to stay flush with sleep
The key to avoiding sleep debt? Consistency. Regular bedtimes and wake times help ensure you’re getting enough sleep to meet your individual needs. Creating a routine that lets you meet your sleep needs is possible with some simple adjustments. For most people, it is easier to adjust bedtimes than wake times – so begin by identifying the time you need to rise in the morning. To determine your bedtime, work backward a full eight hours from your necessary wake time. Spend a week or so on this sleep schedule. If you’re getting sufficient sleep, you should wake feeling rested and refreshed. You should feel able to focus throughout the day, with enough energy to meet both mental and physical demands. Too little sleep will leave you feeling tired in the morning, and fatigued during the day. Your ability concentrate may feel compromised. Pay attention to how you feel, and continue to adjust your bedtime to refine your sleep duration until you find the number that works for you. Once you’ve found the sleep routine that works for you, stick to it – even on the weekends. A regular sleep schedule is your best defense against racking up a large sleep debt.
Getting rid of a sleep debt
Erasing a sleep debt that’s been accrued is best done gradually. If you’ve run short on sleep during the week, it may be tempting to try to catch up with extra sleep on the weekends. Research suggests that this catch-up strategy doesn’t fully remedy the effects of the initial sleep loss. A varying sleep schedule also undermines your body’s ability to regulate sleep effectively. Too much catch-up sleep can leave you wide awake and unable to fall asleep by the end of the weekend. This “Sunday night insomnia” cascades into “Monday morning blues,” as you wake tired from too little sleep. You can avoid this see-sawing sleep difficulty by maintaining a regular bedtime and wake time throughout the week. If you find yourself short on sleep after a stretch of insufficient rest, add no more than 30-60 minutes of extra sleep to your bedtime.
Not too little, not too much
Although insufficient sleep is a much more common problem, too much sleep is also a problem. Sleeping too much can result in feeling tired and fatigued, and lead to health problems. Extending sleep duration also will disturb your body’s finely-calibrated sleep-wake cycles, which can lead to additional difficulty sleeping.
The right amount of sleep is the amount that leaves you feeling rejuvenated, refreshed, and prepared for the day. Identifying the sleep duration that meets your individual needs is the first step toward a lifelong habit of healthy sleep.