Case: 54-year-old with Excessive Daytime Sleepiness

00:00 In this talk, let's discuss the circadian rhythm sleep-wake disorders. Let's start with a case. This is a 54-year-old woman who presents with complaints of excessive daytime sleepiness. The patient reports that this began a few months ago around the time that she changed jobs. She described severe sleepiness during the daytime.

00:22 An Epworth Sleepiness Scale is performed and she scores an 18, which is abnormal and indicates excessive daytime sleepiness. She reports that she has become more forgetful and occasionally will get lost when she's driving.

00:35 Neurologic exam shows cognitive impairment with short-term memory loss, reduced attention and concentration. She denies depressive symptoms. There is no history of head trauma. She does not snore and has not had a history of obstructive sleep apnea. She says that her current job is now a 3rd shift position. She works all night long. She has been having difficulty with adjusting to these new hours. So what's the most likely diagnosis? Is this obstructive sleep apnea? Depression? Delayed sleep-wake phase disorder? Or shift worker sleep disorder? Well, this is not the description of obstructive sleep apnea. That's a common cause of daytime sleepiness, but this presentation is more suggestive of a circadian rhythm disorder and not OSA. Depression is not the most likely diagnosis. Depression can contribute to excessive daytime sleepiness as well as cognitive dysfunctions, but the patient has no associated symptoms to suggest a major depressive or primary depressive disorder. Delayed sleep-wake phase disorder is also not correct.

01:45 The pattern of sleep complaint here is suggestive of impaired sleep quality and duration and that's really not consistent with sleep-wake phase disorder. So this is a typical presentation of shift worker sleep disorder.

02:46 So when we think about circadian rhythm shift disorders, it's important to understand the intrinsic circadian system.

02:53 This is an endogenous biologically active, 24-hour cycle system that controls sleep.

02:59 It keeps us on a regular cycle. It's primarily regulated by the suprachiasmatic nucleus of the hypothalamus. And here, we see that visual input when the eyes open or when light hits the eyes, travels down the optic nerve, and there is one signal that goes right up directly to the suprachiasmatic nucleus of the hypothalamus. The suprachiasmatic nucleus projects to the thalamus and then subsequently to the brainstem to get us awake. And this is how light promotes wakefulness when we arise in the morning. The intrinsic circadian system is influenced by a number of things and helps to control sleep; both the depth, quality, and waking time of sleep episodes. It helps us to maintain wakefulness during the day and modulates many other systems through hypothalamic and thalamic projections. It regulates core body temperature, cortisol secretion, and appetite. So what are circadian rhythm sleep-wake disorders? Well, this is a group of conditions marked by recurrent patterns of sleep disruption. The circadian rhythm is off in some way. What causes circadian rhythm sleep-wake disorders? There are both intrinsic and extrinsic causes. Intrinsic causes include alteration of the circadian system in some way and extrinsic causes are from misalignment between the individual's inner circadian rhythm and the environment. So let's walk through some of the types of circadian rhythm disorders. We'll begin with delayed sleep-wake phase disorder. Here, we're looking at the sleep pattern of the patient over an average week. The patient would typically get in bed around 10 or 11 pm and we see in this disorder a delayed onset of sleep. The patient is unable to get to sleep until 4 am. In addition, we see that the awakening time is also delayed with an awakening time of around noon and importantly the sleep quality and duration is preserved in sleep-wake phase disorder. So basically, sleep is still happening and of sufficient quality but it's much later in the night. Risk factors for sleep-wake phase disorder are puberty, we see changes in the circadian rhythm and melatonin secretion. Caffeine and nicotine use can cause this. Irregular sleep schedules can contribute to this. Depression can contribute to this condition as well as ADHD.

05:33 And typically patients present with difficulty with jobs that start in the morning.

05:38 Sleep is normal when the patient is able to arrange sleep around their schedule and you can think of this as the night owls. These are people who like to go to bed later and wake up later and that can interrupt normal, social, and job interactions.

06:23 Now, let's talk about advanced sleep-wake phase disorder. Here, we're looking at that same sleep pattern over the course of the week and we see that sleep onset is earlier than desired. Patients are going to bed earlier than they would like to.

06:39 Again, the awakening time is also earlier than desired and importantly the sleep quality and duration are preserved. So these are people that are going to bed and sleeping earlier than they would want. Risk factors include older age. As we age, our sleep time becomes earlier and earlier in the day. There is also an autosomal dominant familial variant as a result of missed sense mutations that result in a shorter circadian period. The typical presentation is a patient who just can't stay awake during the evening. These are our early birds. Now let's talk about irregular sleep-wake rhythm disorder. Here, you can see that same typical pattern of sleep over the course of the week and now sleep is significantly disrupted and erratic.

07:28 There are periods of wakefulness and sleep that are not consolidated leading to significant fragmentation of sleep episodes over the course of 24 hours. There is no clear circadian rhythm, no standard sleep time or awake time in these patients.

07:45 dysfunction of the suprachiasmatic nucleus likely plays a critical role. The brain doesn't know when to wake up and there is not a consistent trigger for the brain to wake. Risk factors include neurodegenerative disorders and we can see this fragmentation of a regular sleep-wake rhythm in patients with advanced dementia.

08:04 Patients will report more than 3 bouts of sleep with each one lasting 1-4 hours.

08:10 Now, let's talk about non-24-hour sleep-wake rhythm disorder. So normally, the circadian rhythm is around 24 hours and patients with this disorder will have a circadian sleep-wake cycle that begins greater than or less than that 24-hour period.

08:27 And we can call this a free running disorder. So you see here on Monday night the patient goes to bed around 11 and that normal circadian rhythm would have the patient go into bed at 11 every time of the week. But here, we see that pushed out.

08:41 So it's a progressive free running and lengthening of the circadian rhythm in this patient. The sleep duration is still the same and the quality of the sleep can be maintained but over time progressive dysfunction and excessive daytime sleepiness can occur. In terms of risk factors, blindness can contribute to a loss of the normal sleep-wake cycle and circadian rhythm. Traumatic brain injury can get the brain out of its normal circadian rhythm and we can see alterations in non-24-hour circadian rhythms. And developmental delay can be associated with non-24-hour circadian rhythms. In general, we see insomnia at night in these patients, difficulty with morning arousals, increased daytime sleepiness, and at times patients will have sleep-wake timing that is aligned with the environment. The environment becomes the trigger of that circadian rhythm as opposed to the internal brain's circadian rhythm.

10:17 Now, let's talk about shift worker sleep disorder. So this is impaired sleep cycle secondary to work shift's that are opposite of the normal light-dark cycle. There are a number of risk factors, and an inverted schedule of night shift's is a common contributor to this. Shifts greater than 16 hours can also contribute to this condition. Patients typically present with sleepiness during wakefulness hours, decreased cognition, psychomotor dysfunction may result from the excessive daytime sleepiness, cognitive complaints are not uncommon. Patients may suffer errors, accidents while driving as a result of significant sleepiness during the day. And lastly, what's jet lag? Jet lag disorder is difficulty in initiating and/or maintaining sleep after travel across 2 or more time zones, and this is something that we all may commonly experience. It's affected by travel conditions, mobility, alcohol intake during the travel, and the direction of travel is important.

11:24 We often are more likely to see jet lag being more difficult and to adapt to it when travelling east. Jet lag is typically transient, it's something that happens for a couple of days after we travel and then that normal circadian rhythm sleep-wake cycle pattern should return. The presentation is excessive daytime sleepiness until there's alignment of the patient's circadian rhythm to the light-dark cycle in the new time zone. And somatic symptoms, decreased appetite, constipation can be associated with this condition.

12:23 How do we diagnose a circadian rhythm sleep-wake disorder? Well, the diagnosis is made clinically. Polysomnography or a sleep study is not required but can be performed particularly to rule out other explanations. When we diagnose one of these disorders, a sleep diary is really helpful. It's useful as a self-reported tool to aid in the diagnosis and understand when the patient is going to bed, when they tend to get to sleep, and when they wake up. The patient is asked to record the bedtime, wake up time, total sleep time, estimated time that is required to fall asleep, and the frequency of awakenings at night. And this can help us to put together that pattern of sleep over a typical night and week. Actigraphy can also be helpful. This is a movement sensor worn on a patient's non-dominant wrist to determine the total amount of time and the sleep efficiency. This is useful in cases where a sleep diary is not feasible such as patients with neurodegenerative disorder or stroke or other conditions that may limit the quality of a sleep diary. Melatonin sampling can also be performed in particularly difficult or challenging cases. This can provide an objective assessment of impaired circadian rhythm. Melatonin is the key naturally occurring substance that helps to promote sleep. It's released by the pineal gland around 90-100 minutes before usual bedtime. And it is suppressed by bright lights when we wake up and the light stimulus hits our eyes, this suppresses further melatonin secretion. Dim light melatonin onset protocol can be used to measure melatonin secretion and evaluate for deficiency in melatonin secretion that could contribute to a change in the circadian rhythm. How do we manage patients with circadian rhythm disorders? Well, it depends on the disorder.

14:20 For delayed sleep-wake phase disorder, we talk about sleep hygiene, minimized light exposure during the evening to help bring that sleep onset time earlier in the evening. Light therapy during early morning can help promote a consistent wakefulness and also reset the circadian rhythm to earlier in the night. Melatonin can be administered early in the evening to promote earlier sleep and advancing bedtime each night can also be helpful where the patient starts at his or her normal hour of sleep and then moves it 1 hour earlier each night to the desired onset of sleep. Advanced sleep phase disorder. Management strategies here include light therapy in the afternoon or prior to bedtime, again to help modulate and reset the circadian rhythm. Irregular sleep-wake rhythm disorder. We think about light therapy in the morning to generate a consistent onset of wakening as well as behavioral interventions to consolidate sleep and increase daytime social and physical activities. For non-24-hour sleep-wake rhythm disorder, light therapy to have a consistent on of the brain, melatonin delivered at night to reset that circadian rhythm to a 24-hour period can also be helpful and then some melatonin agonist can be considered in selected patients. For shift worker sleep disorder, we think about light therapy as well as modafinil which can be a helpful wakefulness promoting agent taken at the time that the patient needs to wake up and go to work.

16:02 And then for jet lag disorder, this is often self-limited and doesn't need therapy, but melatonin can be helpful in some patients.