French sleep scientists have studied a group of monks who have virtually no contact with the outside world and have taken a vow of silence.

The monks are of scientific interest owing to the tradition of having two sleep periods per night interrupted by a 2-3 hour prayer and psalm reading session.

The research group were interested in how the sleep-regulating circadian rhythm adjusts to this two sleep system.

It turns out that the automatic rising and falling of body temperature seemed to sync with the two-period sleep patterns but that the monks still had sleep problems (difficulty sleeping, waking, daytime sleepiness).

This suggests that they were not fully adjusted, even after decades of practice (the researchers report that “They all used several (two to six) alarm clocks”!)

Delightfully, the monks were also asked about their tendency to hallucinate and about the content of their dreams.

Although only ten individuals were studied, the answers are oddly appropriate for members of a silent, closed order.

Six monks had experienced mild (n = 4, ringing of the cell door at sleep offset or of the alarm clock, feeling that someone hit them briefly in the back, waking-up during the second sleep while mentally singing psalms) and moderate (n = 2, nightmarish, prolonged feeling of a demoniac presence at sleep onset after Matins) sleep-related hallucinations vs. one control (p = .06). Occasional nightmares were more frequent in monks than in controls. All monks reported dreaming more often after than before the Matins [midnight prayers in between the two sleep periods], and to have conversations in their dreams. These conversations were rare (n = 3), hard to understand (n = 2), or frequent (n = 5). As for prayers, six monks were able to pray while dreaming, although it was rare, whereas two others dreamt of acts of piety, or imagined a disrupted liturgy, and finally two of them dreamt they were never monks.

Link to locked study. Not very charitable really.