 Op verzoek van shorthanded.nl heeft solo-zeiler Huib Swets tijdens de OSTAR zijn slaap/waak-ritme bijgehouden om zo wetenschappelijk materiaal te krijgen voor solide slaap-ritme onderzoek.
Hij heeft daarvoor in opdracht van Gerard Kerkhof (professor aan de UVA) tijdens de hele race een sensor omgehouden dat zijn activiteiten in de gaten hield, verder was licht-monitor aangebracht in de cabine van zijn boot en nam hij voor en na afloop van de race speekselmonsters.
Dat laatste is erg belangrijk om aanpassingen van je biologische klok te meten. Gerard Kerkhof publiceert dit onderzoek in het populair wetenschappelijk blad Mind Open. Het complete verhaal op pagina 4 te lezen. Professor Kerkhof is overigens op zoek naar meer transatlantische solo-zeilers die aan soortgelijk onderzoek mee willen doen.
Uit Mind Open 4 -
Transmeridian sailing
International travel is part of the world of business, including the business of science. Despite its obvious benefits, however, most of us can testify to one annoying drawback, i.e. jet lag. Since most international travel involves the rapid crossing of multiple time‐zones, most traveling colleagues will arrive at their destination with a biological clock that is not adapted to the local day‐night cycle. Subsequently, during several days (roughly corresponding to half the number of time‐zones crossed) after their arrival, they will experience symptoms of sleep loss during the night and sleepiness during daytime. This is the reason why it is not a good idea to attend a late afternoon session in a dark conference room somewhere at the west coast of the U.S.A. on the day following your arrival.
Since jet lag is an inevitable consequence of the speed of transmeridian air travel, an effective remedy would be to travel at a considerably lower pace, so as to allow one’s biological clock to adapt en route. Boarding a cruise ship could be such an alternative, be it an expensive one. It would be more thrilling, though, to travel on a sailing ship, even more during a transatlantic race, such as The Original Singlehanded Transatlantic Race (‘One sailor, one boat, one ocean’). Moreover, if the solo sailor would be prepared to do some simple tests during the race, he would help to clarify what impact his biological clock had on his sleep‐wake behavior on board. Such an opportunity presented itself earlier this year, when I met Huib, one of the 34 international competitors of the thirteenth edition of the OSTAR.
On May 25th this year, Huib started from Plymouth, at the south coast of the U.K., to Newport, Rhode Island U.S.A., more than 3000 miles and five time‐zones to the west. Two weeks before, I met Huib in the seaport of IJmuiden the day before he left for Plymouth and gave him instructions how to wear a wrist‐worn activity monitor, attach another one to the hull of his vessel and a light‐sensitive monitor to the inside of a cabin window and demonstrate how to take saliva samples for the analysis of the 24h pattern of his melatonin secretion.
After 22 enervating days and nights on the atlantic ocean, during one of which the keel of his vessel hit a sleeping whale, Huib finished 12th among the 23 sailors who ultimately reached Newport. After a refreshing recovery sleep of 10.5 hours he sent the recordings to Amsterdam.
Preliminary analyses of the recording of his 1‐minute activity counts (see figure) show that during the 22 days of solo sailing the average 24h amount of his sleep was 2 hours less than during the (baseline) week before his departure, i.e. 6.5 vs. 8.5 hours. Moreover, during the solo period his sleep‐wake behavior was much more fragmented: only 46% of his sleep was taken during the 8 hours of darkness (in bouts with a mean duration of 12 minutes), whereas during baseline the major part (73%) of his sleep was synchronized with the dark period between 11 p.m. and 7 a.m.
Before departure, when asked about the challenges he anticipated, Huib responded: “My biggest fear is how I would cope with sleep, or better, lack of sleep. I have to sleep, that’s for sure, but how long? According to a quick calculation it would take about 15 to 20 minutes
(entirely dependent on the visibility and speed) from the moment a vessel is on the horizon to the position of my vessel. So to be at the safe side, I think I can sleep for about 10 minutes on a stretch. The trick is of course to have multiple 10 minute (power) naps in a row, and in between a very thorough look out, checking instruments, course and speed, sail tuning etc”.
Unfortunately, the saliva samples turned out useless for the analysis of melatonin. So, reliable conclusions about the response of the biological clock have to await another (or the same?) enthusiastic transatlantic solo sailor. I hope this can be realized before the next international issue of MindOpen will be published.
Gerard Kerkhof
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