Sleep is important to every aspect of your physical and mental health. It’s essential for both your mind and body’s daily repair and restoration. Lack of sleep can increase your risk for accidents, type 2 diabetes, heart disease, depression and weight gain, and reduce your body’s ability to fight infections, according to the National Institutes of Health.

A 2013 Gallup Poll reports that American adults are sleeping about an hour less than they did 20 years ago. Even the loss of one or two hours of sleep for several nights impairs your ability to function. It’s equivalent to not sleeping at all for a day or two.

The problems caused by inadequate sleep may not be obvious to you. Besides feeling sleepy or chronically tired in the mornings and during the day, sleep deficiencies can show up as feeling like you could doze off while reading or watching television, riding in a car, after meals, or sitting still in a meeting or movie theatre.

We all miss getting adequate sleep occasionally. Adults need 7-8 hours of good quality sleep in every 24-hour period. Most of us think if we could just get a good nap, we could make up for not sleeping the night before. The National Sleep Foundation’s Sleep Health Index shows that more than half of American adults had napped in the past week: 17 percent napped at least five days a week; 13 percent napped 3-4 days a week; 23 percent napped 1-2 days a week.

While napping probably worked for us when we were children or teenagers, it’s more complicated for adults. A nap that helps instead of harms depends on the person’s health, how much sleep they’ve lost, what activities are planned for later in the day, length of the nap, time of day and quality of sleep. While naps can occasionally be a temporary fix in an emergency, they should not be considered a regular solution for high-quality, restorative sleep.

Here’s what the sleep experts say about naps for adults. The majority of adults should avoid napping during the day if they’ve had problems getting enough sleep the night before. Naps interfere with your ability to sleep at night and throw your sleep schedule into disarray. Napping doesn’t provide the same benefits as night-time sleep; it cannot make up for not sleeping at night. Never expect a nap to compensate for a good night’s sleep.

Let’s look at when napping can help and when it can actually harm you.

When naps can help:

  • Emergency napping can literally be a life-saver when you’re too tired to continue your current activity. For example, drowsy drivers should always pull over and try to nap for 20 minutes. Whenever fatigue interferes with an activity, a quick 10- to 30-minute nap is the most beneficial in terms of reduced sleepiness and improved performance. If you have to take emergency naps frequently or daily, they’re not emergencies; you may have a sleep disorder that requires treatment.
  • Naps that are not close to your normal bedtime – because napping late in the day (past 3 p.m.) can interfere with night-time sleep, according to the National Sleep Foundation. Regular napping can also set you up for creating a habit of inadequate night-time sleep.
  • Planned napping may be occasionally necessary when you know you’ll be up late or have less time to sleep at night. A 20- to 30-minute nap can provide significant improvement in mood, alertness and performance without interfering with night-time sleep. These naps can increase alertness immediately after the nap and up to a few hours following the nap. A National Aeronautical and Space Administration (NASA) study on astronauts and military pilots found that a 40-minute nap improved their performance by 34 percent and alertness by 100 percent. It also reduced mistakes and accidents.
  • Habitual naps – taken at the same time every day as a part of your daily routine – can be helpful for adults with a chronic illness or condition that is helped by regular rest periods, or who are recuperating from a spell of illness, trauma or surgery. Some older adults find that their mood, energy level and ability to focus are helped by a 20- to 30-minute rest/nap after lunch.
  • Night-shift workers can improve alertness and performance by regular 15-to 20-minute naps before and during the time period of their night-shift.

When naps can harm:

Occasional napping or naps longer than 30-40 minutes can produce these negative effects:

  • Mental grogginess or disorientation, especially if awakened from a deep sleep and if you have to perform immediately after awakening. Grogginess and disorientation was also associated with naps longer than 30 minutes.
  • Interference with regular sleep period – if you already have trouble sleeping at night, a nap to compensate for inadequate sleep at night is not advised. It will only make night-time sleep more difficult to achieve and maintain. A 10-minute nap is best to avoid both grogginess and interfering with your regular sleep period.
  • Higher risk for hypertension – a meta-analysis of nine studies involving more than 112,200 participants found that adults who regularly take a midday nap have a 19 percent higher risk for high blood pressure, when compared to non-nappers. However, that’s wasn’t true for night-shift workers. A nap during their night shift actually reduced their risk for high blood pressure by 21 percent. Researchers explained this difference by human physiology. Blood pressure normally drops at night, surges when we wake up in the morning and then drops again by late morning. Nappers are getting a second surge of blood pressure and that may cause high blood pressure.

These findings are controversial. Another study that was reported by heartwire showed that among 300 middle-aged patients with well-controlled hypertension, a midday nap of about 60 minutes was associated with a lower 24-hour blood pressure reading.

Researchers cautioned that the studies of napping’s connection to hypertension involved naps lasting 30-60 minutes. They could not say what the effect on blood pressure would be from a 10- to 15-minute nap or a nap lasting all afternoon.

  • Higher risk for diabetes – several studies have linked napping with an increased risk for diabetes.
  • Higher risk for weight gain – sleeping less than five hours or more than nine hours per night is the danger zone for weight gain. Here’s how sleep-deprived people gain weight more easily. First, if you’re sleepy you’re likely to have low energy and crave high-calorie foods. Poor food choices coupled with being too tired to exercise combine to create weight gain. Second, lack of sleep increases the stress hormone cortisol, which increases appetite. Third, lack of sleep causes the body to produce more of the hormone that signals us to eat more and less of the hormone that signals us to stop eating.
  • Higher risk for microsleep – Inadequate sleep at night can cause microsleep – brief moments of sleep that occur when you’re normally awake. For example, have you ever driven somewhere and not remembered part of the trip? Been listening to someone speak but missed some information or feel like you don’t understand their point? You cannot control microsleep; it controls you. The danger is that it can increase your risk of accidents. Most people are unaware they are experiencing microsleep.

Recommendations

None of the potentially “good” naps listed above can compare with the restorative and repairing qualities provided by night-time sleep. Make it your personal health priority to get enough restorative sleep every night. Even when your life gets extra busy, never let sleep be the activity that gets squeezed out of your schedule.

Don’t expect naps to make up for lost sleep. They can be essential in emergencies, in cases of illness and for some people with very specific health needs.

Maintaining a regular sleep schedule – go to bed at the same time every night, even weekends, and get up at the same time – is an important part of sleeping well at night. Staying up late or sleeping late disrupts your sleep-wake rhythm (circadian rhythm). Our brains use this rhythm to tell our bodies to sleep or wake up. Resist putting work, household chores or even a good book ahead of eight hours each night.

Fight after-dinner drowsiness by getting off the couch. Do something mildly stimulating to avoid falling asleep such as washing the dishes or a load of clothes, calling a friend, or getting clothes ready for the next day. If you give in to drowsiness, you will likely wake up later in the night and not be able to get back to sleep.

For 25 more tips on sleeping well at night, read “Are You Sleepy?”

Next month, Health Spot will explain the most common sleep disorders.