Chronotype – literally meaning time-type. Are you a morning person or an evening person? Recent research has been uncovering some illuminating and previously little-known truths about our tendency to be a morning or evening type. You may have had a hunch you don’t neatly fit in to one of these broader characteristics for a while – but now genetics and science can back this up. In this article, I will break down what your chronotype means, how it affects children, and the wider implications for health, sleep and parenting.
Genetic sleep variables
How many times have you heard from parents and others that someone has ‘always been a bad sleeper’, or that two children, parented alike, are as different in their sleep habits as is physically possible? Or how often have you come across children who sleep irregularly, and then find out that their parents also sleep in the same way? I’ll bet it’s pretty often. We have loosely blamed ‘genes’ for these characteristics for many years, but there is more and more research being published which explains some of these genetic variables. One of the most studied genetic variations is the chronotype genetic coding sequence – the PER3 gene.
The PER3 gene
There are significant links between the PER3 gene and circadian rhythms and sleep homeostasis – the daily, usually fairly consistent fluctuations in our sleep-wake patterns. This gene seems to play an important role in our sleep regulation, though interestingly, one study suggests that this is not true of every ethnic group and population. For example – it does not seem to have such a strong association in Japan. So, while we need to be cautious with this interpretation, it is certainly true that a gene has been identified which may explain why some people have such strong preferences for being an owl or a lark.
The circadian rhythm regulates many bodily functions, including our sleep-wake pattern, hormonal fluctuations, blood pressure and temperature. There are many variables that can influence our circadian rhythm – including activity level, light exposure and social cues. Some of these can be externally influenced, but our fundamental preference or natural body rhythm seems to be heavily influenced by genetics. There are body clocks at organ and cellular level, all under ultimate control by the suprachiasmatic nucleus in the brain – the master body clock. These clocks affect our daily functioning – influencing our appetite, energy level, physiological function and behavior.
What does this gene do?
The PER3 gene has a variable length. There is a variable code, of either 4 or 5 repeated sequences. The length of the PER3 gene influences how much sleep you need. But it also appears that there are more chronotypes than just the well-known ‘owls’ and ‘larks’. It now seems that these are the extremes of the chronotypes.
In actual fact, ‘bears’ make up the majority of the population – about 50% of us have a non-extreme chronotype. Bear sleep-wake preferences and activity levels follow the sun. They neither enjoy getting up too early, nor going to bed too late. They have most of their energy in the daylight, and don’t have any particular trouble falling asleep at night.
Owls, also known as ‘wolves’ have been extensively studied, as this chronotype is associated with more morbidity and mortality (I’ll come back to this later). Owls/wolves make up 15-20% of the population, and prefer to get up late and go to bed late. Their PER3 gene is shorter, and they genuinely need less sleep than the other end of the chronotype spectrum.
Larks, also known as ‘lions’ prefer to get up early and go to bed early. They also make up 15-20% of the population, and this chronotype is not associated with any particular health or sleep pathology. Their PER3 gene is significantly longer, with 5 repeated sequences, which predisposes them to needing more sleep.
Then we have ‘dolphins’ – which many people may not have heard about as a type before, but you will certainly recognize the manifestation of this chronotype. These people are perpetual light sleepers, have difficulty establishing a regular sleep routine, have frequent nighttime disturbances and are often diagnosed with insomnia. Dolphins make up about 10% of the population, but I wonder if they make up a greater bulk of sleep consultations?!
How does chronotype affect parenting?
If you think about it, your chronotype is likely to significantly affect your experience of parenting because having children may force a change in sleep habits, and may not always be perfectly compatible with their child.
Lark parents may find that with their genetic predisposition to need more sleep, they may suffer more acutely with fatigue than owls, who can probably function with less sleep. Consider a parent and baby group where everyone is keen to discuss their child’s sleep, compare notes and maybe sometimes even show off how well they are coping. A bear parent may be coping really well, especially if they have a bear baby and a partner at the other end of the spectrum who is willing to take the antisocial shift.
But the lark parent who needs plenty of sleep and an early night may be coping significantly less well. But who has ever heard parents objectively and rationally discussing their own chronotype and the impact this has on their ability to cope with sleep deprivation? I haven’t. These kinds of discussions often lead parents to believe that everybody else’s baby is sleeping better – when actually, they may just be functioning better on the same level of sleep deprivation. Research backs this up – as numerous research studies have found than on a mass scale, infant nighttime waking is remarkably consistent in the vast majority of cases.
Practical ways to help a lark parent:
- Get tasks done early in the day
- Begin dimming lights in the evening
- Resist the temptation to stay up until after the late evening feed. Go to bed early, and accept that this means being woken in the evening
- Try to have a nap in the day when the baby does
Owls may have an even harder time than larks. Their difficulty with early starts combined with most babies natural tendency to wake early may deprive owls of a significant amount of sleep. Larks will often find it nearly impossible to get an early night to compensate for an early start and sleep disruption, and also have a tendency to reach their energy peak in the evening – resulting in a constant battle between wanting and needing social or relaxation time in the evening, and the need to get some sleep. Daylight saving is also hardest of all on owls – it forces them to get up even earlier, resulting in less sleep overall. Owls also have a tendency to sleep in at the weekend, having built up a sleep debt all week. This may take the edge off temporarily, but is actually not a helpful strategy long term, as it tends to upset the body clock further.
Practical ways to help an owl parent:
- Take it easy in the morning. Resting is good, even if the parent is not sleeping
- Save up tasks for later in the day
- Naps may not be easy for an owl parent
- If the other parent is a lark or bear, have them get up in the morning, and delegate the nighttime parenting to the owl parent
I suspect dolphins have the hardest time of all – they startle awake as soon as they hear a pin drop, and are probably the most likely to struggle to go back to sleep after nighttime disturbance. I suspect a disproportionate number of those babies and children labelled ‘bad sleepers’ may be dolphins – light sleeping, irregular sleepers, who resist multiple efforts to establish bedtime routines and kick up a fuss at bedtime.
Practical ways to help a dolphin parent:
- Enlist help where possible
- Work on the sleep hygiene and sleep efficiency of both parents and children
- Use sensory supports such as white or pink noise to mask breakthrough noise
- Have strong bedtime routines and stick to them
There may not be any easy answers to altering a more difficult chronotype, but there are some general recommendations to try.
How to improve the sleep habits of a more difficult chronotype?
The most difficult chronotypes are probably owls and dolphins. With a few adaptations, most bears and larks can adjust fairly easily to sleep disturbance. Owls and dolphins are likely to have a harder time. Here are some general tips to improve sleep efficiency and sleep hygiene:
- Have a regular bedtime routine, stick to the same time every day, and do not have a lie-in at the weekend. This is especially important for a dolphin, who may find it very hard to establish a regular rhythm. Of course, if there has been an unusual amount of sleep deprivation – for example, being awake most of the night with a sick child, then a compensatory sleep is a sensible strategy, but in general, a lie-in will only confuse the body clock further
- Use sensory supports, such as scent – which can act as a trigger. Scent receptors can become powerfully associated with particular actions, behaviours or memories. Always using the same scent at calm down time or bedtime will help with this. Also, try to use pink noise or white noise to help the sleeper to ignore breakthrough sounds. Cool the room prior to sleep – your body needs a drop in temperature to trigger sleep. In fact, the longest stretches of sleep usually coincide with the core body temperature dropping. You’ll want to ensure the temperature doesn’t reach an extreme low, or this may also trigger a wake up, but it is certainly not true that a warm room induces sleep in general.
- Work on sleep efficiency. This is the amount of time you spend in bed versus the amount of time you are actually asleep. Lots of insomniacs know that they need to catch up on sleep, so they go to bed early. What this does usually is ensure that the bedroom and bed itself are associated with wakefulness, rather than sleep. Lying awake in bed will program your brain to be alert and awake, which will make the problem even worse. Ideally, you will only spend about 15 minutes awake in bed, and then slowly drift off to sleep. If you are wide awake, tossing and turning, getting annoyed, or frustrated, get up and go into a different bedroom. I often talk to older children about reading their books or doing homework in another room altogether if they have begun to take a long time to fall asleep. Then only return to the bedroom when they are really tired. This is often referred to as fading. You deliberately restrict the amount of time spent in bed, to ensure that the time the child or adult is in their bed is predominantly spent asleep, with very little awake time. As this becomes more reliable, you can bring the bedtime earlier.
- Be alert to nap needs. A badly timed nap with a dolphin or owl child will rob them of much needed evening rest and sleep. Ideally, these will be well-spaced in the middle of the day. An owl may naturally need less sleep, remember, and a dolphin may startle awake at the slightest noise. So those children that wake if somebody steps on a creaky floorboard may not be able to tune out those noises. Therefore, try to have naps somewhere quiet and undisturbed.
- Tune in to sleep latency. Be observant to signs of sleep deprivation and overtiredness. This is often the easiest thing to fix, and can have a marked improvement on the rest of the night – whether adult or sleep needs work! Your magic number: 15. 15 minutes to fall asleep, and you’ve got it about right.
- Use light to help. With both dolphins and owls, they may need more powerful environmental sleep triggers. Start dimming lights at least 2 hours before the intended bedtime, and lower the stimulation and activity level at the same time. In the morning, get outside as early as possible, and expose to bright light. A lightbox can be used for people who have a hard time with energy levels in the morning, or consider buying broad spectrum lightbulbs, especially if you live in an area with lower light levels in the winter months.
How does chronotype affect health and wellbeing?
Owls have been shown to have an increased risk of certain diseases and problems. These include diabetes, neurological problems, psychological problems, more addiction, cardiovascular disease, metabolic dysfunction and even a higher risk of death. This all sounds dramatic! Of course, being an owl doesn’t guarantee a shorter or more disease-ridden life – there are multiple factors to take into account. But it is interesting that even when factors such as increased morbidity from cardiovascular disease are controlled for, the risk of death was still 10% higher in owls.
There may be multiple reasons for this. Owls trying to live in a society that predominantly assumes people are larks or bears may be forced to operate constantly at a time that is physiologically stressful for them. They may never get enough sleep, and of course chronic sleep deprivation is associated with multiple health problems. The increased effort of keeping up with a chronotype other than your own may have the effect of causing an internal body clock that is out of sync with the external environment.
In addition, owls and dolphins being awake on their own at night may have more unhealthy habits, such as drinking and smoking, and they may have more social isolation, as they are alone while others have gone to bed – which could explain some of the psychological problems experienced by owls.
Ultimately, there is very little we can do to alter our genetic chronotype, but for the season of parenthood, certain carefully chosen suggestions may make a difference to parents who are struggling to manage.