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How Circadian Rhythms Impact Your Mood

Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. These natural rhythms are controlled by biological clocks in nearly every tissue and organ of the human body. Reset daily through exposure to the light and dark cycles coinciding with alternating neurotransmitters melatonin and cortisol.

Disruption to these natural biological rhythms more often happens when our sleep falls out of sync with light and dark cycles such as through lack of regular quality sleep, night shift work, jet lag, and exposure to artificial blue light before bedtime. Blue lights from electronic devices at night such as the phone, tv, or laptop, can confuse our biological clocks and act as contributing factors in circadian disruption.

Sleeping tablets are among the most widely prescribed medicines as disturbances

in sleep are associated with a wide range of medical and psychiatric conditions. Systems such as the gastrointestinal, metabolic, immune, and nervous systems can all become directly impacted by what is referred to as chronodisruption, and is linked with the following conditions:

Gastrointestinal System- Reflux or GERD, Irritable Bowel Syndrome, Inflammatory Bowel Disease

Metabolic System- Obesity, Diabetes, Metabolic Syndrome

Immune System- Cancer, Autoimmune Disorders

Nervous System- Alzheimers Disease, Mood Disorders, Anxiety, Schizophrenia


Sleep and wakefulness cycles are an essential biological mechanism used to replenish and heal the body. In humans, sleep disruption is known to alter cognition and performance in a wide variety of behavioral domains including attention, executive function, emotional reactivity, memory formation, decision making, risk taking behavior, and judgment.

Thats because sleep allows a number of nervous system and cognitive functions to take place including memory consolidation in the temporal lobe, emotional processing in the limbic system, and neurotoxic debris clearance in the glymphatic tunnels of the brain. It is really no surprise then that disturbances to one's sleep and circadian rhythm are directly connected to psychiatric conditions like anxiety, depression, bipolar disorder, and Alzheimer's disease.


Decades of research has pointed out connections between circadian rhythms, sleep disturbances, and mood disorders like depression and bipolar disorder in which sleep-wake disruptions are actually included as a part of their diagnostic criteria. In particular, mood disorders are believed to partly manifest as a disruption to the limbic system unable to properly activate, release, and recharge through REM sleep. As a result, loss of REM sleep impacts function to this region of the brain known to lead to emotional reactivity as well as cognitive impairments in attention, memory, and decision making.

Composed collectively of the amygdala, hypothalamus, and hippocampus, the limbic system of the brain regulates our mood and how we process our emotions. Strong activation to this region of the brain occurs during REM sleep suggesting this phase of sleep plays a big role in how we regulate our emotions. REM sleep makes up 25% of sleeping time and occurs every 90 to 120 minutes throughout the night with progressively increasing periods of time. In this last stage of our sleep cycle, we experience vivid dreams and actively engage the limbic system.

Major Depressive Disorder (MDD) is a mood disorder characterized by alterations in mood, typically with increased sadness and/or irritability. Individuals with typical depression frequently report early morning awakening and disrupted sleep. Conversely, in atypical depression, individuals often have later sleep times and sleep longer, but experience daytime fatigue. More specifically, studies indicate reduced latency (time from sleep onset to REM sleep), increased REM time, and decreased slow-wave sleep frequently occur in depression. Interestingly, rates of MDD correlate with modernization of society potentially reflecting increased circadian disruption from blue light at night, shift work, and jet lag. In fact, a meta analysis of 11 studies concluded that night shift workers are 40% more likely to develop depression relative to daytime workers.

Bipolar disorder is characterized by cyclic extreme mood swings between mania and depression separated by periods of normal affect. Similar yet distinct from MDD, there is typically reduced sleep during manic episodes, and insomnia or hypersomnia during depressive episodes. The most consistent finding is reduced REM latency and increased REM density in mania, suggesting that there is not a decreased need for sleep during manic episodes but rather an inability to obtain sufficient sleep. Sleep disturbances often will worsen just before relapse and during mood episodes. Hypersensitivity to light-induced suppression of melatonin has also been proposed to be a trait marker for bipolar disorder.

Although circadian disruption may not be entirely the sole cause, both mood disorders are intimately connected with circadian rhythms and REM sleep. Treatment which includes targeted resynchronization of circadian rhythms to your sleep wake cycle is shown to improve symptoms of mood and psychiatric disorders alike.


Aligning your circadian rhythm with your sleep wake cycle is not always easy. There may be environmental, behavioral, and physiologic reasons behind the misalignment in which all need to be considered.

Establish a Morning Routine

Create a consistent regular wake time in the morning. Exposure to light at this time is the strongest mechanism for synchronizing your master clock and getting you in sync with your natural rhythm. In fact, research has demonstrated with increased exposure to blue-enriched morning lighting both alertness and reaction speeds improve. This step is the most effective at aligning your circadian rhythm with your sleep wake cycle.

Eat with the Sun

We have discovered that how much we eat and when has the potential to synchronize or desynchronize circadian rhythms. Timing your feasting and fasting hours to harmonize with the light and dark encourages this alignment. Eating earlier in the day, with the sun versus the dark hours, is helpful not only for optimal sleep but also for your weight status and metabolic function:

  • Insulin is found to reset your circadian clocks with exposure to light

  • Insulin sensitivity is15% greater in the morning, trending down across the day

  • Reduced blood sugar spike after morning meal vs eating the same meal in the evening

  • 44% greater thermic effect of food in the morning versus the evening

  • Hepatic glucose secretion occurs around 8 am (liver spits out stored sugar), not in the p.m.

  • Early eaters are found to lose 25% more weight than late eaters

Mind the Lighting

Bright light therapy may help shift the circadian system and reset the body's clock. Properly timed exposure to bright light can help advance or delay the sleep cycle. Exposure to bright and artificial lights from laptops, tablets, and phones, prior to bedtime can alternatively disrupt rhythms. Try to avoid screen time, bright and blue lights 60 to 90 minutes before bedtime.

Concentrate on Quality Sleep

  • Establish a bedtime routine

  • Go to bed at the same time each night for 7 TO 9 hours

  • Keep your bedroom cool 60 to 67 degrees, quiet, and media free

  • Designate the bedroom as a sleep or sex only zone

  • Use white noise or ear plugs

  • Avoid caffeine after noon if you are sensitive

  • Limit liquid intake 2 hrs before bedtime

  • Try 2-4 oz of tart cherry juice with natural melatonin

Consider Melatonin

Issues in production of melatonin does occur (naturally in the aging process) in which melatonin declines and is shifted to later hours while production of cortisol increases, peaking earlier in the morning hours. This ultimately equates to issues getting to sleep while awaking earlier in the morning. Administration of a prolonged‐release melatonin in the evening can help to rectify this early onset cortisol production.

Consider adding melatonin to your nighttime routine if you are finding difficulty getting and staying asleep. It is recommended to take melatonin 30 - 60 minutes before bedtime. The safest dosage of melatonin is the lowest amount you can take that is still effective in helping you fall to sleep. Consult with a health professional on the right dosage for you.

Invest in your nightly bedtime routine, get the quality sleep your mind and body needs, and never underestimate your own inherent ability to heal from within.

Wishing you all sweet dreams,



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