Yes, but not safely. In my last post I discussed the topic of driving while drowsy which is different from driving while asleep. When people are sleep deprived because they have not slept enough recently or are sleepy because of certain sleep disorders such as sleep apnea, they are often unsafe to drive due to having microsleeps or even falling asleep at the wheel. There is, however, another less common situation in which people are actually asleep while driving. At least, that is, some parts of their brains are asleep.
This arises in the well known but still mysterious disorder of sleep walking. Sleep walking occurs during arousals from deep sleep. It is most common in young children who get far more deep sleep (stage N3) than adults. In fact, sleep walking may be induced in young children by just trying to get them up during the night. If they begin to sleep walk, they can be directed back to bed without ever coming to full consciousness and will not remember the event the next day. Children are often in such a deep state of sleep that they may not be awakened even by very loud noises. Small children rely on the protection of adults during deep sleep. Adults get much less deep sleep and so are usually easier to arouse during the night if an emergency arises.
Typically sleep walking involves the person getting out of bed and beginning to move about. The eyes are usually open and appear glassy and vacant. Very complex motor movements can occur during sleep walking. Most often this is walking from one place to another. The sleep walker may return to bed. The next day there is usually no memory for the event and the person may be puzzled to find objects moved around in the bed room or house. Even more complex movements may occur. Violence can occur, especially if an attempt is made to awaken a sleep walker. Urination in an inappropriate location is fairly common. Eating may also occur while asleep, as may some efforts at cooking. Generally the individual has no memory of these behavioirs.
It is also possible for sleep walkers to experience dream imagery and even vivid hallucinations. Diagnostically, it may be difficult to differentiate sleep walking with hallucinations from REM sleep behavior disorder (RBD). A common difference between the two is that sleep walking usually is an eyes open behavior while people with RBD usually are acting out dreams in an eyes closed condition.
Sleep walking is sometimes observed during nocturnal polysomnography. At these times an EEG pattern of deep sleep with an arousal is noted with EMG and video activity of major body movement. As the movements progress an EEG consistent with deep sleep continues. What occurs is a sleep state dissociation in which the frontal cortex, responsible for higher judgment and planning, is asleep, while at the same time, motor centers responsible for behavior are active. Thus a person may unknowingly execute complex behaviors.
Some sleep walkers have actually driven, sometimes for significant distances. This is a frightening possibility as sleep walkers can be injured while sleepwalking and most certainly can injure themselves or others while sleep driving. Amazingly sleep drivers have been able to get from one location to another without ever waking up. We do not know how many driving fatalities may have resulted from sleep driving.
The most important aspect of treating sleep walking is preventing injury to the sleep walker or to others who may be present. In my next post I will discuss treatment approaches and safety measures for sleep walking.