EDUCATION

The mechanisms for the benefits of sleep are still being discovered, but there are metabolic byproducts of the brain that are being cleared at night by the deepest stages of sleep in particular. Such toxins have been shown to accumulate and contribute to a dementia-like clinical picture in animals and is a highly suspected reason for sleep deprivation causing cognitive impairment in humans. In addition, the daytime energy expended by the brain is immense and rest is necessary to prepare the brain for processing during the following day.

Sleep dysfunction can manifest as daytime sleepiness with poor concentration, impaired cognitive performance, learning and short-term memory. Psychomotor abilities can be impaired in a similar appearance to alcohol intoxication. While non-REM sleep has been linked with consolidation of memory at night, REM sleep appears connected to perceptual learning, creative problem solving and emotional memory consolidation. The experience of dreaming has been attributed to the release of negative emotions including primitive aggressions, leading to enhanced daytime mood.

Finally, a reduction in sleep quantity has been clearly linked with impaired immune function by mechanisms not well understood. Immune surveillance is not only valuable in the fighting of infections, but in the self recognition and destruction of early cancers before they become obviously detectable. Jobs associated with sleep deprivation have been linked to various forms of cancer and the absence of sufficient rest is likely to have played a role.

Sleep studies in a sleep lab involve more sensors, including an EEG (electroencephalogram) that can more definitively distinguish between sleep and wake as well as the different sleep stages. Home Sleep Studies use algorithms based on movement or vascular tone to make estimations with regard to sleep onset and sleep stages without the need for the potentially cumbersome EEG sensors which get glued to the scalp. The EEG however can also identify nighttime seizures. The Full PSG makes use of EMGs (electromyography) to look for spastic movements of the limbs such as in Periodic Limb Movement Disorder or movements during REM which can suggest REM Behavior Disorder (RBD) where someone is attempting to act out their dreams. The Full PSG includes professional EKG (electrocardiogram) monitoring of the heart to look for nighttime arrhythmias. HSATs will typically monitor heart rate at night but only select devices using predictive algorithms can comment on nighttime arrhythmias such as atrial fibrillation. A PSG can also be valuable for titrating CPAP during the second half of a sleep study, where a respiratory therapist can enter the room and try different masks and settings with a real-time assessment of benefit. With the advent of APAP, home titration of CPAP settings can be done by the machine itself and thus remove the necessity of an in-lab sleep study for titration. Finally a Full PSG includes a night vision camera to assist identifying abnormal nighttime behaviors or activities that have gone unnoticed by the patient.

There are many studies which show that sleep in a sleep lab is often of poorer or surprisingly better quality than sleep at home and thus not representative of the true sleep that the patient regularly obtains. Furthermore, people who have been reluctant to get help for their sleep problems (a large population of people) are particularly hesitant to participate in elaborate studies outside the home, observed by a stranger and tethered with numerous uncomfortable electrodes. Sleep Doc LA has been focusing on new technologies to both test in the natural environment and be easy and comfortable enough that representative, natural sleep takes place. These newer devices are better than ever at detecting true sleep, arrhythmias and even sleep stages, once thought impossible to assess outside of a dedicated sleep lab.

Based on the additional sensors of a Full PSG, anytime nighttime seizures are a concern, acting out dreams or unusual nighttime behaviors are suspected, an 'in lab' study is preferrable. Complex cardiac arrhythmia detection or complex CPAP/APAP/BiPAP titration is preferably done in the sleep lab. Conditions such as Narcolepsy, where sleep stage characterization is of highest priority, is usually best done in the sleep lab. At Sleep Doc LA, we are honest about our capabilities and are able to make high quality referrals to dedicated sleep labs when necessary.