Together, your circadian rhythm and biological clock determine when you feel tired, when you feel most awake, and how much rest your body needs to function most optimally. They’re also telling of your chronotype—Whether you’re an early bird or a night owl. “A chronotype is your body’s natural disposition to be awake or asleep at certain times,” Breus explains. It’s an inherent quality and affects all parts of your daily life, including your appetite, core body temperature, productivity window, and even your ideal time for sex.
Someone who is struggling to figure out how to wake up when tired in the morning is likely working against their circadian rhythm. Or, at least, trying to. For example, a night owl who sets their alarm for 6 am may find their biology is working against them because their melatonin (sleep hormone) hasn’t worn off and won’t until 7 or 8 am, Breus explains.
Ideally, you want to schedule your bedtime and wake time based on your chronotype. That way, your circadian rhythm will stay regulated, resulting in consistent and sound sleep. Fight it, and you’re likely to experience suboptimal sleep, warns Sanam Hafeez, PsyD, an NYC-based neuropsychologist and the director of Comprehend the Mind.