Years back, in a Time magazine feature titled "Drowsy America," the director of Stanford University's sleep center concluded most adults “no longer know what it feels like to be fully alert." The National Sleep Foundation found that about seven in 10 adults are getting too little sleep, and nearly six in 10 suffer from some type of insomnia at least once a week. These people are not simply a little groggy or sluggish, but completely and undeniably walking around as if in a stupor.

Most experts agree that three to four hours of sleep once a week won't cause any long-term problems. You might feel terrible the next day, but you can recover somewhat by going to bed earlier the next evening, or napping if that is an option for you. You may have to force yourself to get into bed at 8:30 or 9 p.m. on evenings when you'd rather be up and about, but do it—your body will thank you.

If you're missing out on more than 10 hours a week, decide to catch up on your sleep now before you further diminish your capabilities. Recovery may take a month or more, but it will be worth it.

Don’t Buck the System
In the now out-of-print book The Organic Clock, author Kenneth Rose observed that each part and function of your body has its own timing. A heartbeat, breathing, speaking, and even hiccupping have their own rhythm. If you sleep too little (or for that matter, too much), you will disrupt internal cycles that required millions of years to evolve.

Rose also found that each of your body’s functions are reset every 24 hours, which parallels the natural daily light cycle. Every essence of your being is subject to this circadian rhythm. Circadian rhythm is the daily cycle of activity in living organisms. Altering that rhythm for a prolonged period will prove to be contrary to your own physiology.

In his little-known book, The 24-Hour Society, Martin Moore-Ede observes that certain times of the day are important to sleep through, such as between 2 and 5 a.m., when human physiology is at its lowest level of alertness. Highest alertness, by the way, is between 9 a.m. and noon, and 4 to 8 p.m.

If you happen to be short on sleep some particular day, light exercise such as stretching or a brief walk is good idea. Your energy level may perk up for an hour or two. If you have the opportunity to nap, that would help as well.

To Nap or Not to Nap
Napping increases your alertness for the rest of the day. Some people nap easily; others can't seem to nap at all. You already know into which camp you fall. The best nap time is between 2 and 3 p.m. Any later and your nap may be too deep, interfering with your nightly sleep. 

Naps are a good subsidy to normal sleep patterns, but they are not a good substitute for regularly getting the right amount of sleep. It’s best not to use naps to catch up on sleep if you short-change yourself nightly. 

Your quality of sleep will be much higher and the immediate benefits more apparent if you nap in a bed or cot as opposed to a chair. Although everyone feels a little groggy for a few minutes after a nap, this gradually subsides. Short naps are more productive than long naps. A short nap will leave you refreshed; a long nap may interfere with your sleep that evening. Naps of 20 minutes or less usually help avoid REM sleep, a stage where you're likely to wake up groggy and stay that way.

To derive the most from your nap time, safeguard the nap area before you nod off by making sure that phones or other gadgets will not disturb you. Post a "Do Not Disturb" sign if that will help.

You might need to readjust your sleeping habits or your pre-bedtime rituals, but getting enough sleep is the key to having enough energy to successfully get through your workday.