Sleep-onset insomniacs have delayed temperature rhythms

It was predicted from free running and ultradian cycle studies that sleep-onset insomniacs would have endogenous circadian rhythms that were phase delayed compared to good sleepers.

Thirteen sleep-onset insomniacs and nine good sleepers were selected to differ only in their sleep-onset latencies as confirmed by polysomnography.

their rectal temperatures were measured over a 26-hour constant routine and analyzed with best-fit Fourier curves including 24-h fundamental and 12-h harmonic components.

The temperature rhythm markers of the insomniacs' rhythms were approximately 2.5 h later than the respective phases of the good sleepers.

The usual bedtimes of the insomniacs fell within the "wake maintenance zone" of their delayed temperature rhythm. The good sleepers had typical bedtimes several hours after their "wake maintenance zone" and closer to their body temperature minimum.

It was suggested that manipulations to phase advance the insomniacs' rhythms would reduce their sleep-onset latencies.

It was also predicted that early morning insomnia results from phase advanced circadian rhythms and that sleep maintenance insomnia results from an abnormal phase relationship between the 24-hour temperature rhythm and 12-hour sleep-alert rhythm.

Circadian Rhythm related insomnia

It has been suggested that two types of insomnia, sleep onset insomnia and early morning awakening insomnia, may be caused by delays and advances respectively of circadian rhythms.

Evidence supports the circadian rhythm phase delay of sleep onset insomniacs.

The present study investigated the phase timing of circadian rhythms of early morning awakening insomniacs compared with a group of age matched good sleepers.

A 24-hr bed rest laboratory session was used to evaluate the endogenous core body temperature and urinary melatonin rhythms. This way lifestyle differences are excluded.

Objective and subjective sleepiness were also measured every 30 min across the session with 10 min multiple sleep latency tests and Stanford Sleepiness Scale.

Maximum and minimum phases of each individual's rhythm were identified using two-component cosine curve fitting.

Compared with the good sleepers, the insomniacs had significant phase advances of 2-4 hours for the temperature and melatonin rhythms. However, the advances of the sleepiness rhythms were not significant.

This latter unexpected result was explained on the basis of variability of sleepiness measures. It was suggested that early morning awakening insomnia arises from phase advanced circadian rhythms which evoke early arousal's from sleep.

Very interesting finding.

Early morning awakening insomnia

Phase-shifting effects of bright morning light as treatment for delayed sleep phase syndrome

Bright light has recently been shown to have phase-shifting effects on human circadian rhythms. In this study we applied this effect to 20 patients with delayed sleep phase syndrome (DSPS) who were unable to fall asleep at conventional clock times and had a problem staying alert in the morning. In a controlled treatment study, we found that 2 h of bright light exposure in the morning together with light restriction in the evening successfully phase advanced circadian rhythms of core body temperature and multiple sleep latencies in these patients. This finding corroborates the importance of light for entraining human circadian rhythms.

The effect of evening bright light in delaying the circadian rhythms and lengthening the sleep of early morning awakening insomniacs.

Past studies have predicted that early morning awakening insomnia is associated with early circadian rhythms, meaning that your body temperature drops way before your bedtime.

Because bright light stimulation in the evening is said to delay the phase of circadian rhythms, we tested it on nine early morning awakening insomniacs.

Sleep was evaluated with wrist motion sensors and their temperature and melatonin level graph were measured as well.

In the initial evaluation, the temperature rhythm phase positions of these insomniacs did appear to be earlier than normal. The subjects were then exposed to bright light stimulation (2,500 lux) from 8 pm to midnight on two consecutive evenings.

Following the evening bright light treatment, temperature rhythm phase markers were delayed 2-4 hours and melatonin phase markers were delayed 1-2 hours. Sleep onset times were not changed but the mean final wake-up time was delayed from 5 am hours to 6 am, resulting in a mean increase of total sleep time of about one hour.

This pilot study suggests that evening bright light treatment may be an effective nondrug treatment for early morning awakening insomnia.

Early morning awakening insomnia

People who go to bed at regular hour but wake up too early for their taste, are called early morning awakening insomnia.

The theory, if I am not mistaken, is that the early morning awakening insomnia people's body temperature graph and consequently their melatoning levels graph is flat, i.e. the difference between high peaks and low peaks is too low, therefore they either don't sleep deep or don't sleep long enough or both.

In this experiment they are trying to increase the difference between high and low by applying bright light therapy in the evening, just before going to sleep. Hm...
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Delayed sleep phase disorder

Summary: If you are someone who can't fall asleep before 2-3-4 am, seemingly no matter what you do, you have delayed sleep-phase disorder, or DSPD. In my opinion this is a a condition that you have brought onto yourself by altering your sleep-clock to accommodate late sleeping. It normally starts in the winter and is worse in the wintertime.

I have a few students who have this issue and I'll do some experimentation with them, and will report back here...

Delayed sleep-phase disorder (DSPD), also known as delayed sleep-phase syndrome (DSPS) or delayed sleep-phase type (DSPT), is a circadian rhythm sleep disorder affecting the timing of sleep, peak period of alertness, the core body temperature rhythm, hormonal and other daily rhythms, compared to the general population and relative to societal requirements. People with DSPD generally fall asleep some hours after midnight and have difficulty waking up in the morning.
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Support for Insomnia: Mindfulness to the rescue …

Many people complain about a difficulty of falling asleep, or alternatively, going back to sleep after they wake up during the night.

What most of these people, the complainers, share is this: they, the moment going to sleep isn't happening quickly enough for their expectations, they start forcing sleep, and at the same time they become concerned, agitated, and begin to think about the effects of not getting adequate sleep on their day tomorrow.

What is in common in all the sufferers are two things:.

1. A misconception of how falling asleep works.
2. A lack of discipline, said in another way a mind that runs off with them.
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