Understanding Depression Public Talk Summaries
Circadian Rhythms, Sleep, and Health
Presented by: Dr. Adile Nexha
Dr. Adile Nexha is a Clinical Coordinator in the Department of Psychiatry and Behavioural Neurosciences at McMaster University. She has extensive experience utilizing wrist-worn actigraphy devices to assess daily patterns of activity and sleep in individuals with mood disorders, and has collaborated with several international research groups to investigate mood instability and the importance of behavioural routine maintenance on mental health. Dr. Nexha presented on circadian rhythms and sleep at the CAN-BIND Public Talk, Understanding Depression.
What Are Circadian Rhythms?
Circadian rhythms are natural 24-hour cycles that regulate various biological processes in our bodies. One of the most well-known circadian rhythms is the sleep-wake cycle, which is primarily controlled by a hormone called melatonin. Melatonin, often referred to as the “sleep hormone,” increases at night to promote sleep and decreases during the day to keep us awake. These rhythms are managed by an area in the brain called the suprachiasmatic nucleus (SCN).
How Do Circadian Rhythms Affect the Body?
The SCN also influences other hormones such as cortisol, the “stress hormone,” which follows an opposite rhythm to melatonin. Cortisol peaks in the morning to help us wake up and stays lower at night to promote rest. Beyond hormones, the SCN also regulates organs involved in metabolism, digestion, and energy levels. This means that behaviors like eating, exercising, and exposure to light all impact our circadian rhythms.
How to Maintain a Healthy Circadian Rhythm
To support a balanced circadian system and improve physical and mental well-being, consider the following tips:
- Keep a Consistent Sleep Schedule: Go to bed and wake up at the same time every day, even on weekends.
- Get Morning Sunlight: Spend time outside in natural light, especially in the morning, to help set your body’s internal clock.
- Limit Blue Light at Night: Reduce screen time before bed or use blue-light blocking filters on devices.
- Maintain Regular Eating Patterns: Aim to eat meals around the same time each day to help regulate metabolism.
- Exercise Regularly: Physical activity supports overall health and helps maintain a stable circadian rhythm.
- Avoid Stimulants Before Bed: Limit caffeine and alcohol intake, especially in the evening
Circadian rhythms influence sleep, metabolism, and mood. Disruptions can lead to mood disorders, but maintaining a structured routine, including proper sleep, light exposure, and activity, can help improve overall well-being.
Chronotypes: Are You a Morning Lark or a Night Owl?
People have natural sleep tendencies, known as chronotypes. For example, some are “morning larks” and feel more awake and productive in the morning, while others are “night owls” and perform better in the evening. Most people fall somewhere in between. Chronotypes also change with age. Children are usually early risers, teenagers tend to stay up later, and older adults often shift back to earlier schedules.
What Disrupts Circadian Rhythms?
Disruptions to routines can negatively impact both physical and mental health. Irregular sleep schedules, inconsistent meal timing, lack of exercise, and exposure to artificial light at night can all cause misalignment in our internal clock. When these disruptions occur, they can lead to problems like poor sleep, digestive issues, reduced focus, and even mood disorders such as depression.
One of the most studied groups in circadian research is shift workers—people who alternate between daytime and nighttime work. Studies show that shift workers have a 40% higher risk of developing depression due to the extreme misalignment in their sleep schedules. Similarly, jet lag, which occurs when traveling across multiple time zones, can also cause temporary circadian rhythm disruptions.
The Role of Light in Circadian Rhythms
Light is one of the strongest regulators of circadian rhythms. Natural sunlight, especially in the morning, helps reset the internal clock. Unfortunately, modern lifestyles keep many people indoors with limited exposure to natural light. Similarly, exposure to artificial light at night can interfere with melatonin production, making it harder to fall asleep. To maintain a healthy circadian rhythm, it’s important to spend time outside, particularly in the morning and reduce screen time at night.
Substances That Affect Circadian Rhythms
Certain substances also disrupt circadian rhythms. Caffeine, found in coffee and energy drinks, can keep people awake longer than their body naturally intends. Similarly, while alcohol may sometimes make people feel drowsy, it disrupts deep sleep stages and leads to poorer sleep quality overall.