Sleep Zone

Night owl or early bird?

Chronotypes: night owls, early birds and social jetlag.

Often it seems there is a moral judgement made about bedtime and risetime. There is that old English proverb that says “Early to bed and early to rise makes a man healthy, wealthy and wise.” Recently there has been a lot of hype promoting getting up at 5am as being the answer to success but how true is this claim?

The truth is that going to bed early and waking early may suit some people, but others struggle to do this. While it might feel like you choose your bedtime and risetime, there is actually a strong biological drive behind this choice. This refers to your chronotype: your body’s natural inclination to sleep at a certain time. Recent research shows that chronotype is strongly influenced by genetics with morningness and eveningness characteristics linked to specific genes. For this reason, it is very hard to change your chronotype, although it will alter across the lifespan, going from a tendency towards morningness in childhood, to eveningness in teenagers, then slowly advancing in the adult years back to morningness in later adulthood.

The chronotype is closely linked to the circadian rhythm. This is the internal body clock that regulates the timing of sleep and other bodily processes (for more info click the following link, why teens sleep later). The circadian rhythm can be shifted by light and following a strict sleep schedule. So, it is possible for someone who is naturally a night owl to eventually get to sleep and wake up earlier than their natural inclination if they regularly follow this routine. However, they may not feel they are at their best until later in the day.

What is your chronotype?

You probably already have a sense of your chronotype. If you are not sure, think about when you would wake or go to bed on a day you are completely free to plan, with no work or other commitments. This might be at the weekend or on holiday. There are several online questionnaires to help you determine your chronotype, the most reliable being the Morningness-Eveningness Questionnaire and the Munich Chronotype Questionnaire.

Night owls represent evening types and early birds or larks describe morning types. However, chronotypes exist on a spectrum, similar to height, with most people falling between these two extremes. The morningness-eveningness questionnaire refers to extreme morning types, moderate morning types, intermediates, moderate evening types and extreme evening types.

Variation in chronotype is thought to have occurred through natural selection to reduce the dangers that come with sleeping, such as risks from predators or environmental dangers. Hunter-gatherers shared the task of staying watch during the night to reduce this risk.

While differing chronotypes may be an advantage in hunter-gatherer populations, modern life tends to have social schedules that interfere with individual sleep preferences for many people, with early starts for school and work.

Social jetlag

Social jetlag occurs when someone’s social clock is misaligned to the circadian rhythm. This can lead to feelings of jetlag such as tiredness, dysregulation of appetite, problems sleeping, lack of concentration and sleepiness during the day. Social jetlag is seen when there is a difference in sleep timing between work or school days and free days. This leads to a large sleep debt building up during the week followed by catching up on sleep on weekends, with the latter sleep being at a time more dictated by chronotype than social schedule. This discrepancy is normally more extreme with late chronotypes.

Chronotypes, social jetlag and health

Various studies have looked at chronotype, performance, physical and mental health. Findings suggest morning types perform better academically, most likely due to the fact they get more sleep, experience less social jetlag, feel more alert in the morning when school starts and show higher attendance.

Eveningness is associated with a higher risk of mental health issues such as anxiety, depression, impulsivity, anger and substance use such as nicotine, caffeine and alcohol. In addition, this chronotype is associated with increased risk of type 2 diabetes, obesity, sleep apnea, and metabolic syndrome. These associations are very similar to those seen with sleep deprivation and are therefore likely to be due to irregular and insufficient sleep caused by wake times not suited to late chronotypes, rather than the chronotype itself.

This has led to scientists suggesting work and school schedules should be adapted to chronotype as much as possible, in order to improve workers and adolescent health. While there has been a shift towards flexible working hours, a UK feasibility study found moving school start times to be unpractical, although there has been some success in America, with late school start times leading to improved academic performance and attendance.

How to minimize social jetlag

If you have a tendency towards extreme eveningness be aware that certain behaviours can enhance this effect and worsen social jetlag. Try to stick to fairly regular sleep and wake times, seven days a week while also aiming for seven to nine hours of sleep (eight to ten hours for teenagers); get outside in natural daylight soon after waking; eat some breakfast; aim to exercise in the first half of the day and not in the evening; avoid naps after 3pm; don’t eat too late in the evening, avoid bright lights and light emitting devices in the hour or two before bed; avoid caffeine eight to ten hours before sleep; and avoid stimulating activities such as work or computer games in the hours before bed.

Christabel Majendie November 2022.

Christabel is a Bristol based sleep therapist and consultant, specialising in helping individuals experiencing a wide range of sleep problems. For more information on her work you can visit her website.

Christabel is not a brand ambassador and does not endorse any product of Sleep Well Drinks Limited.