Humans are diurnal creatures that all follow a relatively similar sleeping pattern, we sleep at night and are active during the day. But some of us prefer going to bed late into the evening, struggling to wake up the next morning without an alarm, while others seem to practically leap out of bed in the morning, yet fail to keep their eyes open past dusk. We all know whether we fit into either the morning type or evening type category, but less well known is that we’re genetically predisposed to these tendencies via our chronotypes. Understanding these chronotypes could be key to better sleep and productivity.
Circadian rhythms and chronotypes
It’s no accident that we tend to sleep when it’s dark and wake when it’s light outside. Every cell in our body knows what time it is and is synchronised to the environment via a master circadian clock, often described as a pacemaker, located in the brain.
When it’s light, our clock tells us to stay alert by suppressing the sleep hormone, melatonin. And when it turns dark, melatonin production initiates, which in turn tells us it’s time to sleep. Put another way, the 24-hour periodicity in sleep/wake cycles are driven by your circadian rhythms. Interestingly, these rhythms and sleep/wake cycles can shift in phase from person to person, and can vary throughout your lifetime.
Some people are genetically predisposed to have advanced sleep phases, which means they prefer to awaken early in the morning and feel most active the earlier hours of the day. They are often referred to as morning types or larks. Whereas other people, prefer to awaken much later in the day and typically feel most active in the late evening. They are described as night owls or evening types and have a delayed sleep phase.
Some studies also indicate that evening types may have circadian periods longer than 24.2 hours, while morning types may have circadian periods under 24 hours. And of course, there are people that fit into neither of these categories who are most typically described as intermediates.
The propensity for an individual to sleep at a particular time is known as their chronotype and there may be more than just evening and morning types. Dr Breus, who is a clinical psychologist and sleep doctor, identified 4 chronotypes while observing differences in circadian rhythms. These chronotypes describe not only a person’s preference to a particular sleep time, but also a tendency for a specific habit and daily routine. These circadian rhythm personalities are associated with animals whose sleep – wake personalities mirrored them.
Bears are the most popular chronotype, with 55% of the population fitting into this category. Just like the namesake, bears tend to follow a normal day normal day-night schedule, and like sleeping for at least 7 hours a night. They are most productive in the morning and feel a dip in alertness in the mid-afternoon, before regaining energy in the evening. They have relatively steady energy levels but will feel lethargic throughout the day if they don’t get enough sleep.
15% of the population fall into this ‘early bird’ category. Lions wake up early and are most active and alert during the morning. While exercising before work may seem like an impossible task for most, Lion’s do this with ease and will continue their morning with action–packed productivity. But as noon strikes, the lion’s energy is slowly draining, meaning a brief siesta may be in order, and by evening they’re completely drained and ready to snooze. Lions need a good night’s sleep to maintain their high energy levels in the morning.
Wolves struggle to wake up early in the morning but when they have to, most commonly for work, they lack energy and productivity until the early afternoon. Their peak productivity is in the evening and they can continue to work later than everyone else, with a preference to get to bed long after midnight. Left to their own devices they will wake up late morning so struggle to sync with the rest of the world’s ‘morning schedule’.
The mammal, which sleeps with half its brain awake, is best described to people who have trouble sleeping and feel tired throughout the day. Dolphins may have an irregular sleep routine and often lay awake at night, ruminating anxiously over the past and future. They are most productive mid-morning to early afternoon. Whilst this chronotype may seem bleak, on the positive side dolphins are known for their extreme intelligence and perfectionism.
Benefits to identifying your chronotype
Understanding your chronotype can provide valuable insights into your sleep/wake cycles, productivity levels and propensity for daily activities, such as exercising and working. People identifying as a wolf chronotype, for example, should be aware that it’s natural for them to sleep 2-3 hours later than a lion chronotype. It could also be better for them to wake up later in the morning and defer difficult mental and physical tasks till later in the day.
This is particularly important to realise in a world that favours the early bird and common belief is those that wake later are flawed or lazy. Productivity is in fact the same for morning and evening types, it’s the schedules that differ.
Understanding your chronotype may also help you track eating habits. A recent review explored the connection between diet and chronotype and found that those self-diagnosed as evening types or wolves, typically have a higher intake of caffeine, alcohol and sugar and lower intakes of fruits and vegetables.
What’s my chronotype?
· You can check out your chronotype using the Dormu sleep personality test.
· Alternatively check out The Power of When quiz designed by Dr. Breus who first coined the dolphin, bear, wolf, and lion chronotypes.
· The Morningness–Eveningness Questionnaire (MEQ) is another tool to determine your sleep type.
Can you change your chronotype?
Your chronotype is largely dependent on your genetic make-up, making it difficult to change your chronotype completely. There are ways, however, to minimise the drawbacks of each chronotype and slightly shift your sleeping patterns.
Evening types can try exposing themselves too high light intensity in the morning and limit exposure in the early evening, thereby initiating the onset of melatonin and promoting sleep later. Likewise, morning types wanting to stay awake later can shift their rhythms by limiting light exposure in the morning and increasing exposure in the evening.
Food and exercise have a similar effect to light–and strategically dieting and exercising at the different times of day can alter your circadian rhythms.
Interestingly, your chronotype changes throughout life. Teenagers, for example, experience a shift in their circadian rhythms, pushing back their bed and wake times, while the elderly experience the opposite shift and tend to lean more towards morning types.
Being able to identify your chronotype may be the key to a better night’s sleep and increased productivity, it may also help in synchronising your alertness levels with daily activities. It’s important that as a society, we recognise that people’s rhythms differ too, as it may just lead to a healthier, happier, and more productive population.