Sleep chronotypes: are you a morning or evening person, and can you change it?

Your sleep chronotype is your body's natural preference for when to sleep, wake and feel sharp. Some people are wide awake at 6am, others hit their stride at 10pm, and most land somewhere in between. Genes and age both shape where you fall, but your chronotype isn't a fixed personality type, and you can nudge it with light, routine and timing.

What is a sleep chronotype?

A sleep chronotype is the timing your body clock prefers for sleep and activity. A 2006 paper in Chronobiology International describes chronotype as largely regulated by the circadian clock, with both genetic variation in clock genes and environmental influences shaping it.

That body clock has a physical home. The National Institute of General Medical Sciences (NIGMS) explains that the human master clock is a group of nerve cells in the brain called the suprachiasmatic nucleus. It controls melatonin production based on how much light your eyes receive, and in the evening it signals the brain to make more melatonin, which makes you sleepy. NIGMS says light and dark have the biggest influence on circadian rhythms, though food, stress, physical activity, social environment and temperature matter too.

So when someone says they're "not a morning person", there's usually real biology behind it. Their clock is simply set a little later than the alarm.

Are you a morning type or an evening type?

Most people are neither an extreme morning type nor an extreme evening type. The 2006 Chronobiology International paper says chronotypes in a population range from extreme early types to extreme late types, with the majority falling between those extremes. A 2017 study in PLOS One, using diary data from 53,689 Americans in the American Time Use Survey, found a near-normal distribution, the familiar bell curve, at every age.

The classic research tool is the Morningness-Eveningness Questionnaire, published by Horne and Östberg in 1976. In their original study of 48 people, morning types reached their daily peak in body temperature significantly earlier than evening types, and went to bed and got up significantly earlier. Interestingly, they found no significant difference in how long the types slept. In that study, being an evening type changed when people slept, not how long.

Here's how the two ends of the range tend to differ, based on the studies above.

Is your chronotype genetic?

Your chronotype is partly genetic, but no single gene decides it. A 2019 study in Nature Communications looked at genetic data from 697,828 people in UK Biobank and 23andMe and raised the number of genetic regions linked to being a morning person from 24 to 351.

The regions were enriched for genes involved in circadian regulation and for genes expressed in the retina, which fits with light being the clock's main signal. Yet the effect of all of them together is modest. Using activity monitors on 85,760 people, the researchers found that the 5% carrying the most morningness variants slept about 25 minutes earlier on average than the 5% carrying the fewest.

The same study used a method called Mendelian randomization and found that being a morning person was causally associated with better mental health, but did not affect BMI or the risk of type 2 diabetes. That's one study, and it doesn't mean night owls are doomed to worse mood. It does suggest the timing question is worth taking seriously.

How does your chronotype change with age?

Your chronotype moves across your life, getting later in the teen years and earlier in adulthood. The 2017 PLOS One study found the average chronotype shifts later during adolescence, peaks in lateness at about 19, and shifts earlier after that. The biggest differences showed up between ages 15 and 25.

The study also found a sex difference: men tend to be later chronotypes than women before 40, and earlier types after 40. And variability narrows with age, so older adults are more alike in their timing than younger ones.

This is why a teenager who can't fall asleep before midnight isn't necessarily lazy, and why many people find themselves waking earlier in their 50s than they did in their 20s. The authors noted that adolescents being the latest chronotypes supports later school start times.

What's wrong with animal chronotype quizzes?

Animal chronotype quizzes, the ones that sort you into four animals such as a lion, bear, wolf or dolphin, are popular, but we couldn't find peer-reviewed research validating them. A search of PubMed, the main database of medical research, turned up no studies testing an animal-based chronotype system.

The bigger issue is the boxes themselves. The research tools used in sleep science, including the Morningness-Eveningness Questionnaire and the Munich ChronoType Questionnaire used in the 2006 study, place people on a continuum. The population data show a smooth bell curve, not four separate groups. A label can help you notice your patterns, but it can also make you think your timing is fixed when the evidence says it shifts with age, light and habits.

If a quiz gets you thinking about when you feel sharpest, that's useful. Just don't plan your life around being a "wolf".

What happens when your chronotype clashes with your schedule?

When your body clock runs later than your work or school schedule, you tend to lose sleep on workdays and make it up on days off. The 2006 Chronobiology International paper calls this gap social jetlag. It says late chronotypes show the largest differences in sleep timing between work and free days, building a considerable sleep debt on workdays that they make up on free days.

In their own sample of 501 volunteers, the authors found associations between chronotype, wellbeing and use of stimulants such as caffeine, nicotine and alcohol were strongest in people up to age 25. Smoking was notably higher in late chronotypes. They concluded these links were most likely a result of social jetlag rather than of lateness itself.

A large UK Biobank study published in 2018 followed 433,268 adults aged 38 to 73 for an average of 6.5 years. Definite evening types had a 10% higher risk of death from any cause than definite morning types, after adjusting for factors such as age, smoking, BMI and sleep duration. The authors suggested this may come from chronic misalignment between internal timing and the timing of work and social life. It's an observational finding, and the increase was small, but it adds weight to working with your clock rather than against it.

The NHLBI notes that sleeping more on days off might be a sign that you aren't getting enough sleep, and that staying up late and sleeping in on weekends can disrupt your body clock. Our guide to catching up on sleep looks at what weekend lie-ins can and can't fix.

How can you work with your chronotype?

You can work with your chronotype by keeping your timing consistent and using light to steer your clock. In a 2019 randomized trial in Sleep Medicine, night owls used practical, drug-free changes: earlier wake and sleep times to change their light exposure, fixed meal times, and timing their caffeine and exercise. They shifted their sleep and wake times about 2 hours earlier with no drop in sleep duration, and reported less depression and stress, with better reaction time and grip strength in the morning.

The NHLBI's healthy sleep habits point the same way:

• Go to bed and wake up at the same time every day, keeping weekends within about an hour of weekdays.
• Spend time outside every day when you can.
• Use the hour before bed for quiet time, away from bright screens, since light may signal the brain that it's time to be awake.
• Avoid caffeine later in the day, since its effects can last up to 8 hours.

If you're a night owl with an early job, protect your morning light and your evening wind-down more than anyone. If you're an early bird, guard your bedtime from late social plans when you can. Our guides to screens before bed, caffeine and sleep and waking up without grogginess go into each habit. The NHLBI notes that shift workers may have trouble getting enough sleep, and our page on mouth tape for shift workers covers daytime sleep.

There's one more piece: making the hours you do sleep count. If your chronotype already squeezes your sleep on workdays, you may also want to deal with snoring or a mouth that falls open at night. The NHS lists nasal dilators or strips for blocked or narrow nasal airways, and devices that keep the mouth closed for a mouth that falls open. Some people use the Titan Sleep System, which pairs nasal strips with mouth tape, for exactly that. Check you can breathe comfortably through your nose with the nose test first. We don't recommend mouth tape for children.

When should you see a doctor about your sleep timing?

See a doctor if your sleep timing is badly out of step with your life despite steady habits, or if you're sleepy in the day even after enough time in bed. The NHS says to see a GP about snoring if you feel sleepy during the day, your breathing stops and starts while you sleep, or you make gasping or choking noises, which can be signs of sleep apnea. Our page on sleep apnea warning signs explains what to look for.

A nose that's always blocked is also worth raising, as is any snoring product if you're pregnant: ask a clinician before trying one. And if you simply can't fall asleep at a workable hour no matter what you try, a sleep specialist can help.

Our pick (paid partner): Titan Sleep System

For people whose snoring or mouth breathing is cutting into already short nights, our pick is the Titan Sleep System. It won't change your chronotype, and Titan's products weren't used in any of the studies above. We haven't tested or ranked products ourselves; this is our recommendation for making nighttime breathing more comfortable.

Titan says the system combines TitanAir Nasal Strips and Titan Bamboo Silk Mouth Tape as one nightly routine. It describes the strips as drug-free external nasal dilators with flexible spring-loaded bands, placed just above the flare of the nostrils on the soft part of the nose rather than the bony bridge. The tape is a bamboo silk strip worn horizontally across the lips, and Titan suggests 20 to 30 minutes of daytime practice before the first night.

Titan says every batch is third-party tested and certified PFAS-free, and its 30-night guarantee refunds you if your sleep isn't better after 30 nights. That's enough time to see whether the system fits into a steady bedtime routine.

Read next

• How much sleep do adults need?
• Can you catch up on sleep?
• Daylight saving time and sleep

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.