Normal train vibration induces sleep

[daveklepper]

Rhythm of the rails - on the brain.  Martin Lenhardt, Bioacoustics Laboratory, School of Engineering, Virginia Commonwealth University, Richmond VA, USA.  

A ubiquitous sight on any rail passenger car is sleeping; but why?  People often complain, in they live near railroads, of sleep deprivation or at least sleep interruption from railroad noise.  What's the difference between inducing or interrupting sleep?  To examine this problem rail car vibration was recorded, with ten samples, on a trip from Richmond to Washington DC on an Amtrak train and the data were averaged.  Vibration data were recorded with a Quest Technologies 1800 Sound and Vibration Meter.  The accelerometer was placed on my knee and in another sample, on the arm rest of the seat. The spectra recorded ranged from ~10 Hz to 250 Hz.  Peak displacement was at the lowest frequency (10 Hz) and the amplitude decreased at about 12 dB/octave to 250 Hz (70 dB @ 10 Hz and 22 dB @ 250 Hz).  Train speed was not known but variability in speed seemed not seem to have a notable effect on the frequency response.  It is postulated that the low frequencies entering the body stimulate the vestibular/auditory system as well as the somatosensory system and it is this multisensory nature of rail car vibration that is involved in inducing sleep.  Somatosensory and auditory neural interactions are well known at the cochlear nucleus, the superior colliculus, the insula and the parietal lobes.  There are neurons that only fire when both forms of stimulation (feeling/sound) are present.  In terms of mechanism, it is hypothesized that the low frequency vibrotactile energy alters the electroencephalogram (EEG) inducing sleep.  To test this possibility, a subject was seated on a speaker enclosure designed to couple sound into a water bladder below the seat into the body similar to riding on a moving train.  Vibration was measured off the body (knee) for frequencies of 30, 20 and 12 Hz.  The alpha EEG lowered in frequency with low frequency stimulation to the body; a process termed entrainment.  Entrainment was not immediate but transitioned in twenty ms.  When external stimulation ceased, the EEG returned to alpha state in 20-30 ms.  Although these are preliminary observations, it appears that vibrotactile stimulation can entrain the EEG into the low frequency regions associated with sleep.

NOTE THAT THIS PAPER ADDRESSES THE SLEEP OF PASSENGERS, BUT ALSO EXPLAINS THE SEVERITY OF THE PROBLEM WHEN LOCOMOTIVE ENGINEERS ARE DEPRIVED OF SLEEP.

[Wizlish]

daveklepper

Rhythm of the rails - on the brain.  Martin Lenhardt, Bioacoustics Laboratory, School of Engineering, Virginia Commonwealth University, Richmond VA, USA. 

Can you provide a link to this paper, or e-mail someone (me!) a .pdf copy?

It would be interesting to have seen the effect of introducing lateral vibration into the experiment.  I have had trouble falling asleep on Amfleet because of some of the lateral motion from the secondary air springing -- even a small amount of side-to-side motion can be "alarming" (probably a learned reflex, but poor for sleep nonetheless!)

Be interesting also to see whether external noise effects (including those that 'couple' to the body in some way to induce physical vibration) are synergistic.

NOTE THAT THIS PAPER ADDRESSES THE SLEEP OF PASSENGERS, BUT ALSO EXPLAINS THE SEVERITY OF THE PROBLEM WHEN LOCOMOTIVE ENGINEERS ARE DEPRIVED OF SLEEP.

Someone should make this specific point in an FRA research report...or re-create the experiment with a specific focus on various cohorts of engine crew (including those with a diagnosis of sleep apnea...)

I'd do it myself if I were going to be a psych major.

 

[northeaster]

Well, that explains why I fall asleep onboard a sleeper in a "New York Minute!" It does not explain why I also fall asleep almost as quickly on a ship or in my own bed. But, seriously, I would think that crew subject to this phenomena could very well have problems especially when combined with erratic sleep scheduling. Thanks for the post.

[schlimm]

Alpha waves are not generally a major part of actual sleep, but are seen in the relaxed period (often hypnagogic) prior to stage I sleep.  Some alpha intrusion is seen in REM sleep, when vivid dreams tend to occur or in meditation with eyes closed.  None of those conditions would be advisable for the train engineers.

[cx500]

Don't know if it's the same thing, but I found I could accidentally fall asleep when riding in a RDC while I had much more difficulty in a coach.  I assumed it may have been the background noise and/or vibration of the motor.

John

[daveklepper]

Wizlish, pleasecontact the author at his university.   thanks!

[oltmannd]

The natural frequency of a passenger car's vertical suspension is about 0.5 Hz. The horizontal suspension is similarly low.   Those accelerometers used in the test would miss most of the vibration that occurs.

[dakotafred]

It's seldom you hear from strangers about their sleeping habits. One of those few opportunities is over breakfast in the dining car. You hear everything, leading you to believe that people's sleeping habits are as various in the sleeping car as they are at home.

One of my favorites, from a recent trip, which has the flavor of something borrowed: "I slept just like a baby. Woke up crying every 15 minutes."

I'm one of those who's in tune with the vibrations, falling asleep before I'd really like to and staying there. (I should do so well at home, but at home I'm not paying good money to sleep.) I can't shake the feeling I'm missing out by not looking out the window, even at night.