Tag Archives: circadian rhythm

Timing Light Therapy and Melatonin Supplements

It’s been fun to talk with people suffering from Delayed Sleep Phase over the last couple days.  There’s been some questions about shifting sleep phase using light therapy and melatonin supplements.  The timing of these therapies depends on whether you want to delay sleep, ie. make it begin later, or advance sleep, making it occur earlier.  Once you know that, then you use the Phase Response Curve to see when to use these therapies.

A word of warning:  The correct timing is crucial, so it is best to work with a sleep professional if you want to shift your sleep phase.  If you use light or melatonin therapy at the wrong time you can cause problems by shifting your circadian rhythm the wrong direction.

Follow this link to the Phase Response Curve on Wikipedia: http://en.wikipedia.org/wiki/File:PRC-Light%2BMel.png

On the horizontal axis you see time, and the sleep period written in.  On the vertical axis you see hours of phase advance on the top, and hours of phase delay on the bottom.  Bright light is represented by dark purple, melatonin by green.  Note that the light curve goes both higher and lower than the melatonin, that is because a much larger phase shift can be achieved with light.

Let’s look at an example.  Say an adult is unable to sleep until 2am, but must get up for work at 7am.  Getting 5 hours of sleep each night is not enought for her.  She would like to sleep from 11pm to 7am, but is just not sleepy.  Using the Phase Response Curve, she begins using light therapy each morning when she gets up for the day.  She also takes some melatonin 6 hours before bed.   These combined therapies allow her to feel sleepy at 11pm, and fall to sleep easily.  Now she can get a full night’s sleep, and all the benefits of sufficient sleep.

Are you an Owl or Lark?

An ‘Owl’ is someone whose body clock is set to sleep later than average, and a ‘Lark’ is someone whose set to sleep earlier than average. It is your inherent melatonin rhythm and temperature rhythm that determine when you sleep.

Being an Owl or Lark can impact how well you do with different schedules. Generally speaking, Owls do better with later schedules and shift work like graveyard. Larks are the ones you’d want to open the shop in the morning. It’s important to know that alertness fluctuates over the 24 hours in almost the same curve as temperature. As your temperature drops you are less alert and more sleepy.   If you get into bed and try to sleep before your body is ready, you may experience this as insomnia.  About 10% of chronic insomniacs actually are Owls, and if they go to bed later have no problem sleeping.

To determine if you are an Owl or Lark you can do the Horne-Ostberg Morningness-Eveningness questionnaire, which was developed in 1976. You can find a modified version of it online at http://web.ukonline.co.uk/bjlogie/test.htm.

This information can help you develop a lifestyle that best suits your circadian rhythm.  If you are not able to shift the time of your commitments, a sleep specialist may be able to help shift your circadian rhythm.

Zeitgeibers

What is a zeitgeiber???

The word ‘zeitgeiber’ comes from the German language, and means ‘time giver.’ Zeitgeibers are clues in the external world that help keep our internal body clock in sync with the 24 hour day/night rhythm. This word is used a lot in the field of chronobiology.

The most meaningful zeitgeiber is light, as it impacts melatonin, which in turn sets our circadian rhythm. Other zeitgeibers include meal times, exercise times, and social activities. When your zeitgeibers happen at close to the same time each day, you will be more firmly in sync with the 24 day/night rhythm. This can pay off in sleeping well, and being fully alert during the day!

Lessen the Effects of Shiftwork

About 20% of Americans do shiftwork, starting work either in the late afternoon or in the middle of the night.  Their health suffers, and their relationships can suffer too.  If you are on a shiftwork schedule, here are some strategies to manage the shiftwork lifestyle well.

– First, establish a wake / sleep schedule that you can maintain most days of the week.  Try to have some of your sleep hours the same, regardless of whether it is a work day or day off.

– Shiftworkers typically get less sleep than those who work during the day.  Adjust your schedule to allow enough sleep time, close to 8 hours each night is probably needed.

– To help you sleep those hours, make your bedroom ideal for sleeping.  It needs to be cool, dark, relatively quiet, no pets, and no lit clocks.  If you are trying to sleep during the day this can take more effort, but it will be worth it.  Get blackout shades, or use an eyecover.  Keep a fan running softly or earplugs to keep it quiet.  Train your pets that you are not available during your sleep time.  Set the alarm to wake you up, and then ignore the time, allowing yourself to be ‘off duty.’

In our 24 hour society people will need to work at all hours.  With a thoughtful strategy working shifts can be easier.

At The Institute of Naturopathic Sleep Medicine, Dr. Darley provides care for people of all ages who have sleep problems. More at http://www.naturalsleepmedicine.net/

Your Cortisol Rhythm and Sleep

Cortisol is an intrinsic hormone we all have. It is secreted by the adrenal glands on a regular daily basis.  There is a daily fluctuation in levels, called it’s circadian rhythm.  Cortisol should be low at night while we sleep.  It rapidly rises in the early morning, helping us have the energy to start our day.  Cortisol also can increase due to acute stress, such as an auto accident, or can be chronically elevated due to a chronic stressor.  It is thought that after long periods of chronic stress the adrenal glands get fatigued, so that cortisol is abnormally low.  Cortisol is typically elevated in depression, and low in Chronic Fatigue Syndrome (CFS).

So how does our cortisol levels affect our sleep? 

Cortisol is a wake-promoting hormone, so it can contribute to insomnia when it is high.  In my naturopathic sleep medicine practice we evaluate cortisol when the patient reports high stress levels and difficulty sleeping in the middle of the night.  Salivary cortisol levels are typically tested at four time points throughout a day – 7am, noon, 4pm and midnight.  The patients results are then compared to the normal profile. 

What will help normalize cortisol levels?

Many nutrients are needed by the adrenal glands to function well.  These include vitamins C, B6, and zinc and magnesium.  Some botanical medicines will also support adrenal function.  When the 24 hour cortisol profile is abnormal, supplements are typically recommended for 3 months, then levels are re-tested.  As always, it is equally (or more) important to address the underlying reason that the cortisol has gotten out of balance.  Behavioral approaches to decreasing stress include deep breathing, progressive muscle relaxation, good diet with avoidance of caffeine and alcohol, and good relationships.  If you suspect your cortisol levels may be affecting your ability to sleep consult with a physician for evaluation and treatment if necessary.

For more information about Naturopathic Sleep Medicine go to http://www.naturalsleepmedicine.net.

Melatonin, the Sleep Hormone

You have probably heard of melatonin, one of our bodies’ endogenous hormones. Today we’ll talk about natural melatonin cycles, how melatonin relates to health, and also how melatonin is taken as a supplement.

Your Natural Melatonin Cycle
Melatonin is a hormone produced by the pineal gland. It also acts as a neurotransmitter. In dim light conditions melatonin levels will start to rise about 2 hours before your habitual bedtime, and peak about 2 hours afterwards. This increase is partly responsible for tired feelings before bedtime. It will decline during the night and be at very low levels during the day. Melatonin is suppressed by bright light, such as sunshine.

People who are either “larks” or “owls,” have a melatonin rhythm that is different from the norm. This causes them either to get sleepy much earlier in the day – “larks”, or much later than usual – “owls.” An example is found during puberty in teenagers whose melatonin rhythm shifts later, causing their sleep and wake times to shift later.

Uses of Melatonin
Melatonin can be taken as a supplement to improve sleep. In the past, higher doses (5-10mg) were used like a pharmaceutical drug, and some people experienced a hang-over effect the next morning. Newer research has shown that much lower doses (.3-3mg), which are in line with the levels naturally found in the body, are just as effective.

– Precisely timed melatonin can be used to shift the habitual sleep time for those people who are “owls” or “larks.” Exposure to bright light can also be used to shift sleep times as it will suppress melatonin.
– Melatonin can be used by travelers to reduce jet-lag symptoms. It is especially effective when used in combination with a well-thought out sleep schedule, bright light exposure and limiting light with sunglasses.
– Melatonin can be a gentle aid in promoting sleep for those who have sleep onset insomnia. There are also time-released formulas for people who have difficulty staying asleep through the night.

You can always take advantage of your endogenous melatonin rhythm by going to bed at approximately the same time each night, and getting bright light exposure in the morning. This is one way to naturally keep your sleep healthy!