Sleep and Fatigue — Page 220, Lesson 352

I want to walk you through a worked example of how a pilot can manage sleep around a disrupted schedule, and then we’ll look at the principles of sleep hygiene that support good-quality rest when the body’s natural rhythm is out of sync. Let’s start with Solution 2. This is a sleep strategy for a pilot facing a duty pattern that crosses time zones or involves irregular hours. The pilot takes a short first sleep of 1 hour 20 minutes, then stays awake to enjoy the local nightlife. After that, they have a further sleep period to build up enough sleep credits before a third and final sleep period immediately before the duty day begins. I’ll walk through the table so you can see exactly how the body clock and sleep credits line up. The table has four columns: State, Local Time, Body Clock Time, and Sleep Credits. From 2100 to 2220 local time, which is 0200 to 0320 on the body clock, the pilot is asleep. That first sleep gives them 2 hours 40 minutes of sleep credits. Then from 2220 to 0100 local — 0320 to 0600 body clock — they are awake, and sleep credits are zero. Next, from 0100 to 0500 local, which is 0600 to 1000 body clock, they sleep again, and that gives them 8 hours of sleep credits. Then awake from 0500 to 1300 local — 1000 to 1800 body clock — credits stay at zero. Finally, from 1300 to 2100 local, which is 1800 to 0200 body clock, they sleep for a third time, and that yields 16 hours of sleep credits. Now, the advantages of this pattern. First, the times when the pilot is awake are more sociable — they can interact with others during normal local hours. Second, both the first and last sleep periods will be of good quality because the sleep credits are zero at the start of each, meaning the body genuinely needs sleep, and body temperature is on the decrease, which naturally promotes sleep onset and depth. The disadvantages are significant. The sleep pattern is very disrupted, and it will be hard to stick to the schedule. Also, the middle sleep period will be of poor quality because body temperature is rising at that time, which works against deep, restorative sleep. Now let’s move to sleep hygiene. Sleep hygiene is the set of practices that help you fall asleep and stay asleep when your body’s natural signals aren’t aligned with the clock. The key principle here is that if your body really needs sleep, it will sleep under almost any condition. But if you are trying to sleep while you still have sleep credits — meaning you aren’t yet tired enough — or at a time of low circadian sleepiness, then you need to actively help the process. Here are the specific sleep hygiene guidelines from the book. First, avoid drinks containing caffeine near bedtime. That includes coffee, tea, cola, and a number of fizzy soft drinks. Caffeine affects both Stage 4 sleep — the deep, restorative stage — and REM sleep, which is important for memory and emotional regulation. Importantly, when caffeine is removed from a drink, the sleep-disturbing effect is also removed. Also note that aspirin contains caffeine, so that counts too. Second, avoid napping during the day. Napping can reduce your sleep debt and make it harder to fall asleep when you need to. Third, make sure the room and bed are comfortable. Exclude any daylight, ensure air conditioning is working, and make sure insects — especially the biting or stinging variety — cannot enter the room. Fourth, avoid excessive mental stimulation and emotional stress before bed. Fifth, a warm milky drink, light reading, or simple progressive relaxation techniques will all help to promote sleep. Sixth, avoid alcohol and heavy meals. Alcohol may help you fall asleep initially, but it disrupts the later stages of sleep, and heavy meals keep your digestive system active when it should be resting. So to summarise: Solution 2 shows a three-sleep strategy that maximises sociable awake time and good-quality first and last sleeps, but at the cost of a disrupted pattern and a poor middle sleep. Sleep hygiene gives you practical tools to improve your chances of falling asleep when your body clock isn’t cooperating.