Interview with a sleep doctor: "Switching off is the be-all and end-all"
Kristina Müller
· 06.11.2023
YACHT: Dr Hein, why is a good night's sleep so important?
Dr Holger Hein:During sleep, we can break down circuits in the brain that we have built up during the day and that are unnecessary, isolated from the environment. We decouple what is important and store it.
But how do you get a good night's sleep on board and especially at sea?
By switching off well. That's the be-all and end-all. At sea, this works best if you know that everything is OK. That means you should know your boat well, know where everything is and be able to find your way in the dark. Then you don't have to worry.
Do you have another tip?
Warm feet! If they are cold, you sleep badly. This has been scientifically proven. On board we also have the advantage that we are not subject to as many impressions as in everyday working life in a city. The impressions on the water are more uniform, so you can perhaps manage with a slightly shorter regeneration time.
The impressions on the water are more uniform, so you can also manage with a shorter regeneration time"
Is it even possible to sleep as deeply on board and at sea as in bed at home?
Yes, a distinction is made between the three sleep phases of light sleep, deep sleep and dream sleep, i.e. REM sleep(REM stands for Rapid Eye Movement, as the eyes move quickly during this phase; editor's note).You can go through all these phases on board with the same intensity - regardless of whether you sleep through the night in one go or fragmented, i.e. in intervals.
Many cruising sailors organise their watch system according to the natural inclinations of the crew and so that everyone gets six to seven hours of sleep in a row. Others sail with significantly shorter watches. What do you think is better?
I think shorter intervals of around four-hour watches make more sense, because after that the guard's concentration wanes. I recommend a forward-rotating system so that the same person is not always on dog watch.
But isn't it much more difficult to fall into a deep sleep during a short free watch, which this system entails for the typical crew of two?
Not necessarily. Fragmented sleep is not bad in itself. The main thing is that you can switch off well.
How can you do this without first undergoing personalised sleep training?
Tips from cognitive behavioural therapy are to think about nice things, such as positive experiences during the day, and not about problems. At night, they are greyer and more difficult to see due to the hormonal starting point, because then the mood-lifting cortisol level goes down and only rises again in the morning. Routines on board also help you to switch off better during sleep. It is important to know what your own sleep rhythm is, i.e. whether you are more of an early or late sleeper. You should stick to this on board.
During the night watch, you often keep yourself awake with coffee and chocolate bars. Is that actually a good idea?
Drinking something warm is definitely good, because cold makes you tired. Chocolate, on the other hand, doesn't keep you awake for long. Wholemeal products are better. However, I recommend keeping your waking hours between midnight and four o'clock as short as possible, about two hours.
Single-handed sailors don't have the choice. Especially during regattas, they repeatedly report hallucinations due to lack of sleep. When do you get them, what happens in the body?
Approximately when you are awake for 36 hours, from then on it gets worse. The brain is no longer tidied up and can no longer categorise old connections. It no longer knows: is something happening now or has it already happened? Then you see or hear things that aren't even there.
How much sleep is enough afterwards to clear the brain?
Two to three hours in itself. And then, when sailing single-handed, sleep again and again in portions.
Not easy when the adrenalin is keeping you awake! How should the role of stress and tension be assessed, especially in regatta sailing?
Adrenalin is also quickly broken down again. But if you are under constant stress and are constantly releasing cortisol, regeneration no longer works well. In this respect, you should make sure that you get the amount of sleep you need. After all, sleep is not a state in which you are completely out of it. There is an interesting report by Ellen McArthur about how she sails at the drift ice edge and suddenly realises that the ship is moving less. This is beautifully recorded with the actigraph, a motion sensor. The ship's movements become less near the iceberg, which wakes her up.
If you think about yourself a little, you realise what is good for you. There is no panacea"
As athletes, ocean racing sailors are particularly dependent on a good night's sleep - which is not easy when sailing. What advice would you give them?
Basically, exercise during sport supports good sleep, even when sailing. When you sleep, you can also have lucid dreams, i.e. you dream about what you want to achieve in terms of sport. There are studies on this from other sports. Many people can dream lucidly if they make a firm commitment to it. This can help to increase success.
Finally: What do you think of sleep techniques such as fantasy journeys, audio books or listening to music?
That depends. Some find it annoying, others don't. But I'd rather listen to music than an exciting thriller. If you think about yourself a bit, you realise what's good for you. There is no panacea.
About the person: Dr Holger Hein
The sleep physician runs a sleep laboratory in Hamburg and a practice in Reinbek. He has already advised Boris Herrmann and charters regularly on the Baltic Sea and the Mediterranean. YACHT readers are welcome to send him their experiences on the subject of "sleep on board" by e-mail to: hh@dr-holger-hein.de
