The Dolphin Chronotype
The Light Sleeper (Breus estimates ~10% of people)
Breus describes Dolphins as light, easily woken sleepers with busy minds at night. Energy tends to be uneven in the morning, with focus settling from mid-afternoon.
Lion, Bear, Wolf and Dolphin come from sleep psychologist Dr. Michael Breus's book The Power of When (our summary). They're popular shorthand for morning–evening preference, not a clinical diagnosis.
A Typical Dolphin Schedule
Morning
- Natural Wake Time6:30 AM
- Peak Focus Hours3:00 PM - 7:00 PM
Evening
- Typical Last Coffee*~5 h before bed
- Wind Down10:00 PM
- Target Sleep11:30 PM
*Caffeine for a Dolphin: With an 11:30 PM bedtime, one average cup finished by about 6:30 PM would usually be below 50 mg by bed. Dolphins are light sleepers, though, so start conservatively: keep to one or two cups early in the day. If caffeine seems to linger for you, choosing the slow setting in ARC moves your cutoff earlier.
There's no universal cutoff. For one average cup and an average metaboliser, caffeine takes roughly five hours to fall below 50 mg; a bigger cup, a slower metabolism, or an earlier coffee still in your system pushes that earlier. ARC works it out from your bedtime, how fast you clear caffeine, and everything you've logged today.
Morning light: About 20 minutes of outdoor light each morning (longer under heavy cloud; never look directly at the sun) gives a Dolphin's clock a clear, consistent signal. A steady wake time, even after a bad night, matters more than trying to catch up with a lie-in.
How to Tell You're a Dolphin
- • You wake at small noises and take a while to drop off
- • You often wake before your alarm and can't get back to sleep
- • Your mind gets busy at bedtime
- • Mornings feel uneven, and you settle into focus later in the day
Are you sure you are a Dolphin?
Take our free 2-minute, 8-question quiz to estimate your chronotype.
A Sample Dolphin Day
- 6:30 AMWake at the same time, even after a rough night
- 7:00 AMAbout 20 minutes of outdoor light and gentle movement
- 8:00 AMFirst (and maybe only) coffee
- 10:00 AM - 12:00 PMRoutine work; don't expect peak focus yet
- 3:00 - 7:00 PMYour steadiest focus
- 7:00 PMLow-stimulation evening: light dinner, no heavy news
- 10:00 PMWind down; write tomorrow's to-do list
- 11:30 PMSleep
Times are illustrative. Your own day depends on your wake time and commitments.
Calming a Dolphin's Evenings
Real dolphins sleep with one half of the brain at a time while the other stays alert, which is where Breus got the name. Human Dolphins tend to need more time than others to wind down. Keep evenings low-stimulation (no intense news, hard conversations or complex work late), avoid heavy dinners, and dim the lights for the last couple of hours.
Try writing tomorrow's to-do list before bed. In one sleep-lab study, people who did that fell asleep faster than people who wrote about what they'd already done (Scullin et al., 2018). If you have trouble sleeping at least three nights a week for three months, talk to a doctor: cognitive behavioural therapy for insomnia (CBT-I) is the first-line treatment.
✓ Strengths
- • Attention to detail
- • Can function on less sleep if necessary
- • Perfectionistic drive
✕ Challenges
- • Light, easily broken sleep
- • Anxious energy
- • Hard time winding down at night
Strengths and challenges as Breus describes them; individuals vary.
What ARC Changes for a Dolphin
Knowing your chronotype helps most when your day actually follows it. ARC uses your chronotype to set the phases of your day, then gives you one sentence explaining why you feel the way you do right now, and one next step at the top of a short day plan.
ARC won't treat insomnia; it's a wellness app, not a medical device. What it does for a Dolphin is keep the timing steady: a consistent light window from your real sunrise, a wind-down reminder before bed, and a caffeine cutoff that moves earlier if you tell it you clear caffeine slowly. After a short night, ARC adjusts the day plan instead of leaving you to guess.
Read more: stress, cortisol and trouble falling asleep, building an evening wind-down, and the evening light and melatonin guide.
Frequently Asked Questions about Dolphins
Why do Dolphins have trouble sleeping?▼
Breus describes Dolphins as light, easily woken sleepers who stay mentally alert at night. That's a description, not a diagnosis. If you have trouble sleeping at least three nights a week for three months, talk to a doctor: CBT-I (cognitive behavioural therapy for insomnia) is the first-line treatment.
Should Dolphins take melatonin supplements?▼
Melatonin is mainly a timing signal rather than a sedative, and when it's used, low doses (0.5 to 1 mg) are common. Dimming lights for the last couple of hours before bed helps too. Evidence for supplements like L-theanine and magnesium is weaker than for melatonin. Talk to a doctor or pharmacist before starting any sleep supplement, especially if you're pregnant, breastfeeding or take medication, and don't give melatonin to children without medical advice.
Is the Dolphin chronotype scientific?▼
Lion, Bear, Wolf and Dolphin are sleep psychologist Dr. Michael Breus's popular labels from his book The Power of When, not a clinical diagnosis. The science underneath is real: people differ in how early or late their body clock runs, partly for genetic reasons, and researchers such as Till Roenneberg measure it on a continuous scale rather than in four boxes. Treat "Dolphin" as useful shorthand for where you sit on that scale.