Your circadian rhythm (sleep-wake cycle) is most heavily influenced by light in your surrounding environment, but can also be affected by temperature, physical activity, and social interactions. When your body’s internal clock isn’t synchronized with these external cues, you may feel tired but still have trouble sleeping,.

Your biological clock

There are many parts of your brain that pick up on these external cues like sunlight, which then initiate signals to be sent to a brain structure called the suprachiasmatic nucleus (SCN). The SCN uses this information to control many different processes in your body, such as digestion, hormone regulation, body temperature, and sleep.

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Dr. Colleen Ehrnstrom's profile picture
Dr. Colleen Ehrnstrom, PhD

Dr. Colleen Ehrnstrom is a licensed clinical psychologist with a specialty practice in Acceptance and Commitment Therapy (ACT). Areas of expertise include insomnia and other sleep disorders, anxiety, and depression.

Dr Ehrnstrom is the co-author of the book End the Insomnia Struggle: A Step by Step Guide to Help you Get to Sleep and Stay Asleep which offers a comprehensive, personalized sleep program that integrates the physiology of sleep, cognitive behavioral therapy for insomnia (CBT-I) and acceptance and commitment therapy (ACT).

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