For those who have not guessed, the answer and the subject of this short article is sleep!
Sleep is an essential component of a healthy mind and body. While there are different types of sleepers, humans generally follow fairly similar patterns of sleeping.
The Sleeper Cycle
The sleeper first begins by falling asleep (stage N1), i.e. he is between awake and asleep, without really feeling asleep. He then enters light slow wave sleep (stage N2), which leads to deep slow wave sleep (stage N3) in about 20 minutes. This one is characterized by a slow brain activity. This is a restorative stage, from which it is difficult to wake up. After 60 to 75 minutes of this regime, the famous REM sleep (stage R) appears. In this phase, the brain experiences intense activity, close to that of awakening, while the body remains inert. The sleeper's eyes move rapidly under his eyelids and he dreams. This stage lasts 15 to 20 minutes. These phases make up the first sleep cycle. The sleeper then alternates between deep slow wave sleep and REM sleep during the first half of the night, then between light slow wave sleep and REM sleep during the second half. These cycles are repeated 4 to 6 times in one night.
Sleep on the run
However, you will understand that long nights are rare, if not impossible in the context of sailing races. So, how do you manage fatigue? The single-handed racer must adapt to fractional sleep (called polyphasic sleep), composed of several cycles separated in time, instead of a full night of cycles following each other (monophasic sleep). Sailors generally adapt to this rhythm within 48 hours. However, the sleep of the first 24 hours is of poor quality, lacking the restorative stage and REM sleep. These one reappear after only a few days. The resting time is then divided into 4 or 5 episodes of about 20 minutes to an hour, if the weather conditions allow it. Crewed racers must get used to cutting their sleep and wake up quickly for their night shift.
Preparing for sleep
Fortunately, there are strategies to help your body adapt to such rhythms. Resting before a race to avoid starting the race with too much fatigue and knowing your sleep cycle is a good start. The shift system in a crewed race can also encourage a routine that will facilitate the transition to fragmented sleep, as long as you always take the same night shift. It is recommended that you do not fall back to sleep if you wake up on your own about 15 minutes before the start of your shift. It is still advisable to maintain a state of wakefulness, for example through dialogue between teammates. Since sleep is only one component of the crew's general health, it is also important to ensure that energy intake is sufficient and well distributed throughout the day to avoid exacerbating the effects of fatigue. Finally, it is important to know that maintaining a polyphasic sleep pattern over a long period of time can have significant health consequences, such as a collapse of the immune system or a depressive state, hence the importance of being monitored by a medical team. We hope to have enlightened you on this subject and wish you a good night!