Sleepiness During Real Driving at Night

We know that driving while sleepy is dangerous. Driving in the middle of the night is especially dangerous. Most studies of driving while sleepy have been on driving simulators, which are not the same as real driving. In the October edition of the Journal Sleep, a study was done to assess sleepiness on real driving. Researchers measured subjective sleepiness, the position of the car relative to the driving lane, objective measure of sleep by measuring brain waves, the duration of eye blinks, line crossing, and speed of vehicle. There were 18 normal sleepers in good health. Study subjects were monitored while driving during the day and night.

Results showed that subjective sleepiness, eye blink duration, and brainwave-measured sleepiness were higher during nighttime driving compared to daytime driving. Also, drivers were more likely to veer toward the middle of the road at night, and this is a new finding. The authors thought it could be due to desire not to go off the shoulder from sleepiness and from reduced visibility of the shoulder. Another new finding was that speed was slower at night and the authors thought this could be due to sleepiness and/or a need to be safer because of decreased visibility.

This study gives us more evidence of the dangers of nighttime driving. And the subjects in this study were healthy and not sleep-deprived. Imagine how much more dangerous these drivers would be if they had a sleep disorder and/or were sleep-deprived. Try to limit nighttime driving if possible. If you do drive at night, be safe and smart about it.

Obstructive Sleep Apnea and Psychiatric Patients

Obstructive sleep apnea is becoming more common, especially as obesity rates increase. Some of the medications used to treat psychiatric conditions can contribute to obesity, putting these patients at risk for OSA. There was data presented at the recent American Psychiatric Association where a screening questionnaire was given to patients that were admitted to the hospital for psychiatric illness. The screening tool is called the STOP BANG and can be downloaded from here. Of the 85 patients studied, 46 (54%) were positive on the OSA screening questionnaire and 10 of those (22%) had OSA confirmed. The researchers concluded that these 10 patients would have gone undiagnosed if not for the simple screening process. Since some of the symptoms of OSA overlap certain psychiatric illness (fatigue, sleepiness, insomnia), screening patients could help identify those at risk for OSA and get them the needed treatment.

Prevalence of Sleep Paralysis

Sleep paralysis occurs when a person becomes completely paralyzed when either going to sleep or waking up. The only muscles that can be moved are the eye muscles and the diaphragm. It is very frightening because the person is awake and usually thinks they are dead or have had a massive stroke. The symptoms last only a few seconds to minutes, but can recur regularly. It's associated with another sleep disorder called narcolepsy, but sleep paralysis can also occur by itself. It's a harmless condition by itself, but it's important to get evaluated and treated if it is part of narcolepsy.

A study was done recently to determine the lifetime prevalence of sleep paralysis. Researchers reviewed 35 studies on the condition and determined that almost 8% of the general population has had at least one episode. Prevalence was over 28% for students and 32% for psychiatric patients - possibly due to more disrupted sleep and changes in sleep schedules seen in those populations.

Difficulty Breathing During Anesthesia and Obstructive Sleep Apnea

I'm not an anesthesiologist, but I always learn cool things about sleep from them - after all they are always putting people to sleep. Apparently, there is an association between patients that are difficult to intubate and obstructive sleep apnea (OSA). Now there is a study that was done to determine if patients that are difficult to ventilate with an anesthesia gas mask are at risk for OSA. If so, then anesthesiologists would be able to identify potential patients and refer them on to a sleep center for diagnosis and treatment.

I can see the connection between difficulty using a mask to ventilate (abbreviated DMV) and OSA because the two conditions share similar risk factors - elevated weight, older age, male gender, increased upper airway crowding, and a history of snoring. When a patient is under general anesthesia, their throat is more relaxed and could collapse more easily. This could contribute to difficulty ventilating with a gas mask.

In this study, ten patients had sleep studies after full recovery from surgery and a minimum of 30 days after their operation. The sleep studies showed that all ten subjects had some degree of OSA, with 80% having moderate to severe OSA. The more difficult to ventilate with a mask, the more severe the OSA. The results are interesting but there are limitations to this study. The average time between surgery and the sleep study was 7 months and 2 days with a maximum time of 21 months. Therefore, keep in mind that patients could have gained weight during the time from their surgery to the sleep study, and that weight gain could have increased their risk of OSA. Also, all of the study subjects had similar characteristics known to be associated with OSA - elevated weight, large collar size, more snoring, more high blood pressure, and more daytime sleepiness than the general population. Therefore, these characteristics could be responsible for the high amounts of OSA, not the DMV. Finally, there was no control group, so it's not known how many patients without DMV would also be diagnosed with OSA.