Sleep: Getting too much or too little?

Most of us feel like we don’t get enough sleep. But what exactly is enough? And regardless of how much we get, just how good is our sleep?

On 13 June 2011, in Minneapolis, Minnesota, Ron Grunstein, Professor of Sleep Medicine at the University of Sydney, will receive the prestigious Nathaniel Kleitman Distinguished Service Award from the American Academy of Sleep Medicine.

Professor Grunstein, the first non-North American to win the award, will be acknowledged for his significant contribution to professional development in the field of sleep medicine and in researching into the relationships between obesity, metabolic dysfunction and sleep apnoea.

Hopefully his success will prod the rest of us to pay closer attention to the state of our sleep.  But I’m not so sure. Sleep doesn’t seem to rate in dinner party conversation quite as high as other medical disorders.

Up until the turn of this century, it was widely held that five hours or so of sleep a night was adequate to keep one’s mental performance operating smoothly. People simply made do with less sleep. Before long that idea was put to bed, given it grew out of studies where the researchers sent sleepy heads home during the day, where they may or may not have sneaked in a double shot skinny latte or two. Who knows?

An internationally recognised expert in the biological limits of human performance relative to sleep need and circadian biology, David F. Dinges, Professor of Psychology in Psychiatry at the Hospital of the University of Pennsylvania, in 2003 assigned tens of subjects over two weeks to one of three groups: some who slept eight hours (the control group), some six hours and the rest four hours.

He applied a Psychomotor Vigilance Task to the subjects every couple of hours to determine their attention spans. As Maggie Jones in the New York Times Magazine explained, this task involved placing the subjects in front of computer screens for short periods and asked to tap a particular key when they saw a flash of numbers at random intervals: not unlike a visual field test used by ophthalmologists to confirm visual deficits. A delayed response indicated a lapse into sleepiness, commonly called a “micro sleep”.

For good sleepers, the test is like watching paint dry. Boring! But if you’re short on slumber (in both quantity and/or quality), then the test is frustrating. Its purpose is to verify continuous attention that is vital for say, pilots, truck drivers and fire fighters.

The control group (those sleeping eight hours), as hypothesised, hardly had any attention gaps and suffered no memory lapses over the two-week study. Those in the four and six-hour groups had results that skidded steadily with each passing day. Though the four-hour subjects performed far worse, the six-hour group wasn’t that far behind.

Conclusion: for most of us, eight hours of sleep is good and six (or less) hours is bad.

Poor sleep was the anecdotal reason why the lone U.S. air traffic controller at Washington’s Reagan National Airport was enjoying 40 winks, on the job, when two airliners landed in late March, without air traffic assistance. The planes, American Airlines flight 1012 from Miami, a Boeing 737, and United Airlines flight 628T from Chicago, an Airbus A320, with a combined 165 people on board, touched down landed safely at 5:45am.

This episode highlighted a long-known and often ignored hazard: Workers on night shifts, whose sleep is poor, can have trouble staying awake let alone concentrating.

"Government officials haven't recognised that people routinely fall asleep at night when they're doing shift work," claimed Charles Czeisler, Professor of Sleep Medicine at Harvard Medical School and Chief of Sleep Medicine at Boston’s Brigham and Women's Hospital to Randolph E. Schmid, the Associated Press’s science writer on 16 April.

“So the notion that this [sleeping on the job] has happened only a few times among the thousands of controllers is preposterous," he boomed, three days later to Boston’s Fox 25 Morning News program on 19 April.

The potential catastrophic consequences of snoozing are of course not limited to air traffic controllers, but apply across the board to many professions. Think vital services: police, state emergency services and our soldiers in Oruzgan Province in Afghanistan. And less vital: City Rail workers and Road and Traffic Authority staff.

And poor sleep hygiene is not confined to shift workers.

Many of us (including me) do get enough sleep at night but still doze off – for short periods - during the day. Every day. This is called “excessive daytime sleepiness”. Why do we do this? And for the record, just how good or how bad is our sleep the night before we exhibit EDS?

Gregory Store, Emeritus Professor of Developmental Neuropsychiatry at Oxford, in Insomnia and other Adult Sleep Problems explains the two distinct types of sleep: NREM and REM sleep.

NREM sleep makes up three quarters of adult sleep and is divided into four levels of increasing depth, called ‘stages’. Stage one is the lightest sleep and stage four is the deepest sleep. Each stage has its own sort of brain activity, as recorded by an electroencephalogram or EEG. The eyes are still, most muscles are relaxed and both breathing and heart rate are steady.

Slow EEG activity is absent in stages one and two but is present in the deep sleep typical of stages three and four. In deep sleep both eye movements and muscle activity are decreased.

NREM, characterised by being in the main devoid of dream activity contrasts with REM sleep, which involves accelerated heart rate and shallow breathing. Eyes dart rapidly in various directions, hence the name Rapid Eye Movement.  REM is where most dreaming takes place.

Our need for sleep is a function of two variables – the duration that we have been up and about and our in-built body clock, commonly called the ‘circadian body clock’, which regulates when we sleep within each 24-hour period.

High quality sleep is sound, unbroken and deep. It is restorative enough so that we can function properly the next day without the need for daytime kips. While some people make do with sleeping just a few hours, most of us need close to eight hours. To know if you get enough sleep, simply ask yourself if you tire during the day or if you ever feel drowsy enough in the day to warrant a nap?

Putting aside unusual nocturnal behavior like sleep walking and sleep terrors (grouped together as parasomnia), there are two fundamental sleep disorders – not sleeping well (called ‘insomnia’) and too much daytime sleeping (called “hypersomnia”).

Insomnia is a nighttime inability to get to sleep and/or to stay asleep.

Hypersomnia or “excessive daytime sleepiness” is usually explained by: fragmented or poor quality sleeps the night before (due to many reasons including stress, work or family relationships) or an abnormal need for sleep (such as narcolepsy or depression). When doctors can’t find the root of excessive sleeping, they’ll brand it as idiopathic hypersomnia).

Excessive sleepiness can also occur in a variety of neurological conditions.

If you’ve experienced problems over say two months getting to sleep or staying asleep; not feeling rested when you awake; being told you snore loudly or taking short naps most afternoons, then complaining to your general practitioner may result in a referral to a sleep specialist who will inquire into your sleep history, medical history and could recommend an overnight sleep study (which is not painful, just uncomfortable if my experience is anything to go by).

There are two tests, night and day. The night test is universal and the latter is performed only if you suffer daytime sleepiness.

The night time test involves an overnight stay in a sleep clinic, which may be a hospital room, where countless electrodes are attached with glue to the scalp (to track brain waves); under the chin (to measure variances in muscle tension); near the eyes to determine eye movements; inside the nostrils to gauge air flow; on the legs to confirm restless leg syndrome. Hooking you up involves you getting into your pyjamas and sitting on a chair head bowed motionless for 45 minutes while a sleep technician attaches countless electrodes to facilitate monitoring.

If the technician fails to draw the blinds in your room, feel free to do it yourself. Afterall the entire objective is as sound a sleep as possible. Once you’re tucked in bed, by about 9:30 pm, the technician will turn on the CCTV. So remember to smile! I kid you not, the infrared camera is quite a distance from the bed but the nurse could clearly see when I countermanded her instructions and grimaced when asked to smile.

Trying to sleep under these conditions with the best of intentions is, to be fair, very, very difficult. But not painful at all. I suppose it’s a lot like after pitching tent, trying to get 40 winks, on a hard surface, on a wet night, in a sleeping bag when you’re middle aged. Using the same bag you used in high school, that is.

Before the technician switches off your room’s lights from her workstation at 10:00 pm sharp, over the intercom you’re told that a nurse will arouse you at 6:30 am. Trust me, your sleep will be more fragmented than usual, on account of the strange place you’re at as well as the many electrodes attached to you, that you’ll be up well before your 6:30 visitor.

Oh and at 6:30 you’ll be dragged out of bed. No ‘five more minutes please, I am so tired’.

Dressed, having eaten breakfast, some three hours later you’ll begin the Multiple Sleep Latency Test, which is a series of 4 or 5 twenty minute naps taken at 2 hour intervals, starting anywhere from 9:30 am to 10:00 am. You’ll be told to get in or on to the bed. The lights will go out and your job will be to fall asleep. Some 20 minutes later you’ll be roused and told to move out of the bed and into the chair.

The purpose of the MSLT is to determine how long it takes a person to fall asleep and the depth of that sleep. Does the person enter the REM zone? That is, does dreaming take place?

Prior to and during the MSLT no unauthorised naps are to be had nor is caffeine (or any other stimulant) allowed. Vital medications are of course permissible.

If you fall asleep during the daytime test too quickly then you’ve got a problem.

There is little or no discomfort during the MSLT.  Small electrodes or patches remain from the night time study glued to the scalp and various areas of the body and some equipment, like the leg monitors (keeping a look out for restless leg syndrome) will be removed.

You remain in the same hospital or clinic’s room. You will continue to be monitored by closed circuit TV and an intercom. From the moment the electrodes were attached to your scalp the night before, until after the MSLT you cannot shower. In fact the closest you get to look or smell reasonable is by brushing your teeth.

Bring a book or hope daytime TV has something worthwhile to watch. Some clinics have DVD players. And bring a water bottle with a small spout. Trust me on that (remember what I said about electrodes all over your head, face, nose and near your mouth?)

You’ll be allowed to leave at around 5:30 pm after the electrodes have been taken off your skin.  Note glue residue left in your hair can be shampooed out.

The MLST test proves or disproves the presence of excessive daytime sleepiness (EDS). Why EDS takes place is another question.

You’ll find the night and day tests are very illuminating inasmuch as they reveal:

• How long you actually sleep for, which may be at variance with how long you think you sleep. It was in my case.
• If your sleep is more restless than you thought (i.e. do you suffer from Restless Legs Syndrome?). That’s a “no” in my case.
• If you may suffer a particular sleep disorder (such as sleep apnoea or narcolepsy) and will be told what treatment options are available.
• If unexplained excessive sleeping is confirmed as it was in my case, you will not know why you suffer it, as there is no definitive test to answers that. Possibly it is a consequence of a brain hemorrhage, but nobody knows. Possibly it’s just “me”.

Relief from excessive daytime sleepiness, no matter its cause, is available by prescription. The stimulant drug modafinil (marketed as Provigil) is the specialist’s first choice of treatment. It is believed to be less likely to be abused than other meds. Other meds include the far cheaper, dextroamphetamine and to a lesser extent methylphenidate (marketed as Ritalin).

Possibly one in four people suffer from a sleeping disorder of some type. Some of which can be life threatening. Assuming you’re free of psychological or psychiatric problems - which could keep you up for other reasons - ask yourself or your partner the following: Do you snore? Fall asleep when you don’t intend to? Wake up at night and don’t need to go to the bathroom? Or don’t enjoy sound and uninterrupted sleep?

If yes to one or more, then you may have a disorder. The sooner you get it checked out, the better. Whatever you do, don’t sleep on it.