Sleep deprivation isn't always obvious.

"Sleep debt" (or sleep deficit) is the difference between the amount of sleep you should be getting and the amount you actually get. This difference represents a deficit which increases every time we skim some extra minutes off our nightly sleep.
"People accumulate sleep debt surreptitiously," says psychiatrist William C. Dement, founder of the Stanford University Sleep Clinic. In fact, studies have shown that such short-term sleep deprivation leads to a "foggy brain", worsened vision, impaired driving and problems in short-term memory. Long-term effects include obesity, insulin resistance, and heart disease.
And most Americans suffer from chronic deprivation. A 2005 survey by the National Sleep Foundation reports that, on average, Americans sleep 6.9 hours per night -6.8 hours during the week and 7.4 hours on the weekends: experts recommend eight hours of sleep per night.
The problem is that after a long period of sleep deprivation, you stop realizing how tired you actually are.

In a study by the University of Pennsylvania School of Medicine, researchers followed three groups of subjects for 14 days; one group slept for eight hours a night, the second group slept for six hours a night, and the third group slept just four hours a night. Cognitive tests after the two-week period showed that the people with only six hours of sleep a night showed similar reaction times as people with a blood alcohol content of 0.1 percent; a level which is considered legally impaired.

Other studies have indicated that a consistent lack of sleep may cause permanent damage to your brain. 
One in particular, also conducted by the University of Pennsylvania School of Medicine and published in The Journal of Neuroscience looked at lab mice that were kept awake to replicate the kind of sleep loss common in modern life, through night shifts or long hours in the office.
The team studied certain brain cells which are involved in keeping the brain alert. After several days of sleep patterns similar to those followed by night workers - three days of night shifts with only four to five hours sleep in 24 hours - the mice lost 25% of the brain cells in vital parts of the brain stem.

After only a night or two of sleep deficit, a few nights of adequate sleep are usually enough to reverse the effects and "recharge" your system. But chronic sleep deprivation may be harder to recover from.
For information on how to increase your sleep drive and improve your waking hours, take a look at our  sleep hygiene recommendations. If you have a problem with daytime sleepiness and you have increased your sleep length without improving your daytime sleepiness, then you should be evaluated by a Sleep Disorders Specialist. With proper care most people can obtain the treatment they need to improve this problem.

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References:
Sleep-Deprived People Can’t Tell They’re Sleep-Deprived; Melissa Dahl, NYMag.com
Lost sleep leads to loss of brain cells, study suggests; Helen Briggs, BBC News

Fragmented sleep could be as physically harmful as a total lack of sleep.

It will come as no surprise to new parents struggling after a night of feeds or doctors on call, but being woken up in the night is as detrimental as getting just four hours of sleep. Just one night of interrupted sleep may negatively affect mood, attention span and cognitive ability according to a new study from Tel Aviv University, published in the journal Sleep Medicine.

In the last 50 years, sleep research has focused on sleep deprivation, and practically ignored the impact of night-wakings, which is a pervasive phenomenon for people from many walks of life. Directors of the study hope that their work will bring this to the attention of scientists and clinicians, who should recognize the price paid by individuals who have to endure frequent night-wakings.

Researchers studied the sleep patterns of 61 healthy adults, 40 of which were females between the ages of 20 and 29 years old, were traced at their homes using actigraphy and sleep diaries. Subjects slept a full eight-hours one night, followed by a night of interrupted sleep in which they received four phone calls directing them to complete a brief computer exercise before returning to bed. The interruptions were designed to keep participants awake for a period of 10 to 15 minutes. The morning after both nights, the volunteers completed tasks to measure their attention span and emotional state: results proved that just one night of interrupted sleep had negative effects on mood, attention span and cognitive ability.

While they found few significant differences between interrupted sleep and sleep deprivation, the differences between the aforementioned conditions and a normal night's sleep were vast. Results indicate an increase in depression, fatigue and confusion in addition to diminished vigor and motivation when sleep is interrupted or restricted.

This means that even when people get a total of seven hours sleep a night, being forced to wake up for regular 15 minute feeds, or consultations, will leave them feeling like they had just four hours rest. “The sleep of many parents is often disrupted by external sources such as a crying baby demanding care during the night,” said Professor Avi Sadeh and a team of researchers from Tel Aviv University's School of Psychological Sciences. Doctors on call, who may receive several phone calls a night, also experience disruptions. These night wakings could be relatively short - only five to ten minutes - but they disrupt the natural sleep rhythm.

These effects accumulate and therefore the functional price new parents-who awaken three to ten times a night for months on end-pay for common infant sleep disturbance is enormous.
Besides the physical effects of interrupted sleep, parents often develop feelings of anger toward their infants and then feel guilty about these negative feelings. The findings bear relevance to substantial portions of the population whose sleep is regularly fragmented including medical students, shift workers, military personnel and parents.
Professionals as well as the general public should be aware of the detrimental effects of the various kinds of disruption in sleep on daily functioning and mood and consider countermeasures to minimise their consequences.

For more information on how you can get a good night's sleep visit our website at HoustonSleep.net.

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References:
Study: Interrupted Sleep May Be as Harmful as No Sleep at All- Melissa Hellmann, TIME Magazine July 9, 2014

Commercial Drivers Still at High Risk From "Drowsy Driving"

The issue of sleep-deprived or "drowsy" driving has made the news again following the tragic June 7 accident involving the comedian Tracy Morgan. Prosecutors say that the Walmart truck driver whose tractor-trailer slammed into a van, critically injuring Mr. Morgan and killing another passenger, had not slept in over 24 hours.
Drowsy driving is a leading cause of crashes and highway fatalities, according to federal officials: more than 30,000 people die on highways annually in the United States and crashes involving large trucks are responsible for one in seven of those deaths.
Federal rules introduced last year reduced the maximum workweek for truckers from 82 to 70 hours, after which drivers have a mandatory 34-hour resting period. This “restart” must include two periods between 1 a.m. and 5 a.m. to allow drivers to rest at least two nights a week: they cannot drive for more than 11 hours a day and must have a 30-minute break in their schedule.

But the trucking industry has been battling to get the new nighttime-break regulations repealed. On June 6, Senator Susan Collins, Republican of Maine, pushed an amendment through the Senate Appropriations Committee that would freeze the rules, pending further studies. Ms. Collins said the administration had failed to take into account that the new rules would put more trucks on the roads during peak traffic hours. Trucking officials and executives also said that drivers needed to be afforded maximum flexibility in their work and should not be told when to rest.

Safety investigators said that sleepy or drowsy driving is a far more common problem than most people realize, but how extensive the problem is remains a matter of debate, partly because it is difficult to obtain evidence that drivers fell asleep. In 1990, a National Transportation Safety Board study of 182 heavy-truck accidents in which the truck driver died concluded that fatigue played a role in 31 percent of the cases, more than alcohol or drugs.
But the American Trucking Associations said that a federal database of fatal crashes cited fatigue in less than 2 percent of police reports about accidents involving trucks; a more accurate estimate, they claim, is that driver fatigue plays a role in about 7 percent of truck crashes. “Until we have a blood test for determining fatigue, all estimates are likely going to under-report fatigue, because the dead don’t speak and the living often plead the Fifth, especially if they are facing criminal charges,” said Deborah A. P. Hersman, former chairwoman of the N.T.S.B. and now the president and chief executive of the National Safety Council.

The Transportation Department has proposed that all interstate commercial truck and bus companies be required to use electronic logging devices to increase compliance with driving-hour rules. Paper logs are easier to manipulate and more difficult for law enforcement officials to verify. The comment period for the rule is scheduled to end this month. Some commercial truck fleets already such devices. For instance, Walmart’s trucks have GPS and electronic logging systems, which track where the vehicles are and what they are doing. A Walmart spokeswoman said the truck involved in the accident that injured Mr. Morgan, who remains in a New Jersey hospital, was also outfitted with anti-collision technology, which is supposed to alert drivers if there is a car in a neighboring lane when they activate their turn signal, for example. It is also supposed to slow the truck down automatically if it is approaching slow-moving or stopped traffic. Citing the incomplete investigation, Walmart declined to provide specifics on the accident or the driver’s schedule in the days leading up to the crash.

Excessive daytime sleepiness is a common problem in today's society. It is so common that in some circles people almost consider it a normal aspect of a productive society. The fact is that daytime sleepiness and fatigue are leading causes of accidents, both on the job and on the road. The cost to society is estimated in billions of dollars per year. There are several common causes for increased daytime sleepiness. The simplest cause of daytime sleepiness that can be corrected results from insufficient sleep. The average person requires 7 to 8 hours of sleep per night. If a person routinely gets less than this, it will most likely cause excessive daytime sleepiness. Another common problem can be sleeping in a noisy environment. This can cause many short awakenings, so brief that a person doesn't remember them the next morning. This results in non-restful sleep with resulting excessive daytime sleepiness. If a person gets 8 hours of sleep a night and still feels sleepy during the day, one should consider that they may have a medical problem which hinders their ability to obtain restful sleep.
For more information on the causes of "drowsy driving" and how you can get treatment for the sleep-related issues involved, visit Dr.Simmon's website at houstonsleep.net.

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References:
Truckers Resist Rules on Sleep, Despite Risks of Drowsy Driving (NYT, June 16, 2014