My body is in London but my body clock is in New York

Mr V is a 21-year-old college student who presented to the clinic with a history of severe initial insomnia. Starting from around the age of 15 years he has had increasing difficulty getting to sleep at night. He would go to bed at around 11 p.m. every night, but found it impossible to get to sleep before 3.00 or 4.00 a.m. During term time he would rise with great difficulty to three alarms and much prompting from his increasingly frustrated parents in order to get to class on time. He struggled with concentration during class, frequently falling asleep, particularly in morning lessons. His concentration and alertness improved in the afternoon, though he was still very tired. Despite his fatigue he found himself becoming progressively more alert in the evening and felt most awake around 12.00–1.00 a.m. He became progressively more depressed and was seen by several child and adolescent psychiatrists. He had some psychotherapy, which improved his relationship with his parents but did not improve his mood or his sleep pattern.

On completing school he took a gap year and worked as a DJ in a nightclub, working from around 10 p.m. to 3 a.m. He then slept from 4 a.m. through to midday and felt much more alert when awake. He also noticed a significant improvement in his mood. However, since starting college he has had to start waking at 8.00 a.m., but has not been able to move his time of sleep onset any earlier than 3.00 a.m. He therefore only sleeps five hours a night at most and has started to struggle at college. His depression has also returned.

Questions

1 What is the likely diagnosis?

2 Why did he feel tired in the morning despite sleeping better on the hypnotic?

3 What investigations would you do to confirm the diagnosis?

4 How do you treat delayed sleep phase syndrome (DSPS)?

5 Are there any other treatments for DSPS?

Answers

1. What is the likely diagnosis?

This history is typical of a DSPS. This is a circadian rhythm disorder where the person has a normal 24-hour sleep–wake cycle, but their internal biological clock is delayed relative to the outside world—‘their body is in London but their body clock is in New York’. They have the same fluctuations in alertness that normal people have, but they occur later. Therefore, they are still feeling very alert late at night when the rest of the world is going to bed, and they only start to feel the normal late-night sleepiness in the early hours of the morning. They have difficulty staying awake in the mornings, as this is their time of lowest alertness—10 or 11 a.m. for someone with DSPS is the equivalent of 4–5 a.m. for everyone else. Similarly, the late evening for someone with DSPS is the equivalent of the afternoon for everyone else, and so it is no surprise that it is difficult for them to initiate sleep at this time. DSPS is more common in adolescents and young adults, though it can occur in any age group. The fact that it is much more common in adolescents than in adults indicates that most people will grow out of DSPS. Around one in ten patients presenting with insomnia may in fact have DSPS and it is important to exclude this disorder in any patient who presents with sleep onset insomnia.

Mr V tried numerous remedies over the years, with very little success. He tried going to bed earlier, but found he simply lay awake until 3–4 a.m. regardless of what time he went to bed. He tried staying up for 36 hours to reset his cycle, and while he sometimes managed to fall asleep in the evening on the first night after doing this, by the second night he had reverted to his usual pattern. In desperation he asked the GP for hypnotics. He was given a prescription, but was advised only to use them if absolutely necessary. He found he was able to get to sleep at a normal time with the hypnotic and sleep through the night, but still felt very sleepy in the morning. As soon as he stopped the medication, he reverted to his delayed sleep pattern.

2. Why did he feel tired in the morning despite sleeping better on the hypnotic?

The tiredness that patients with DSPS feel in the morning has two causes. The first is that, as they cannot fall asleep until late, they are sleep deprived. The other reason is that their circadian alertness drive is at its minimum in the morning and the timing of the circadian clock is not directly affected by sleep. So even if they get an adequate quantity of sleep on a hypnotic, their body clock will still be delayed. Therefore, they will feel the same in the mid-morning period as others would at around 5 a.m. regardless of how much they have slept. However, as the day progresses and their circadian alertness drive increases, their alertness will improve. Indeed, this is what Mr V reported. The hypnotic did not make him feel any better in the morning, but he did feel better later in the day, as he was not sleep deprived.

3. What investigations would you do to confirm the diagnosis?

The diagnosis of DSPS is largely made on history. However, it can be useful to get the patient to fill in a sleep diary and to perform a few weeks of wrist actigraphy. The actigraph measures movement and can give an objective longitudinal view of the patient’s sleep pattern in the real world. If possible, it is helpful to do the actigraphy during a period where they allow themselves to sleep in their natural rhythm, as well as during a period when the patient is working, going to college, etc. and is therefore having to get up in the morning. By monitoring the sleep pattern when they are sleeping in their natural rhythm one can see what that rhythm is, and it also allows one to exclude initial insomnia. If the patient has initial insomnia rather than a DSPS, one would expect to see delayed sleep onset on the actigraph but not necessarily a delay in the rising time. Doing some of the actigraphy when the patient is trying to get up in the morning gives one an idea of how much less sleep they get in these circumstances, which can be useful when advocating on their behalf with work, school, etc.

4. How do you treat DSPS?

As the underlying cause of DSPS is a delay in the internal circadian clock relative to the outside world, the main aim of treatment is to advance that circadian clock. Although there is some complex neural circuitry driving the clock, the clock can be mediated using melatonin and light. Melatonin ‘pulls’ the sleep cycle towards itself while light ‘pushes’ it away. Thus in order to advance the clock one needs to take melatonin before sleep to pull the sleep forward and use light after sleep to push the sleep period earlier.

The timing of the melatonin and light is critical. The times of maximum effect are calculated relative to the person’s natural dim light melatonin onset (DLMO). The DLMO is the time that the person starts secreting melatonin when in a dark environment. However, the DLMO is very rarely used in clinical settings—because the time of the DLMO will move as the therapy starts to take effect, one would need to do it repeatedly and this is not practical. (For more information on how the DLMO is determined, see Case Study 46 (ASPS)). Therefore, we need to estimate the time of the DLMO from the person’s sleep onset time. A good rule of thumb is that the DLMO tends to occur two hours before sleep onset and the best time to give melatonin is about six hours before sleep onset. Obviously one cannot predict the time of sleep onset, so we use the time of sleep onset the night before. Thus the person takes melatonin approximately six hours earlier than the time of sleep onset (NB: time of sleep onset, not the time they went to bed) the night before. They then get exposure to light, either by going outdoors or using a seasonal affective disorder (SAD) lamp immediately on waking for 30–60 minutes. (See Case Study 49 for more detail on how to use light.) This will gradually pull the sleep cycle forward.

Mr V instituted this regime and found that his sleep cycle gradually advanced over a period of two weeks until it eventually settled into a pattern where he was falling asleep at midnight and waking at 8.00 a.m. He was therefore taking his melatonin at 6.00 p.m. Even more striking was that his depression rapidly resolved and his performance at college improved, as he was much more alert during the morning classes.

5. Are there any other treatments for DSPS?

Chronotherapy is an alternative technique that is sometimes used. Trying to go to bed earlier each night is a strategy that rarely, if ever, works. But doing the opposite can be quite effective. The patient sets aside a week or two to undergo the chronotherapy and they then go to bed an hour or two later each day. This means their period of wakefulness is longer than usual and so it is much easier to initiate sleep. As a result, their sleep–wake cycle becomes progressively delayed until they are sleeping in phase with the outside world. Once this happens, the chronotherapy is stopped and the regime with melatonin and light is instituted to hold the person in phase.

Learning points

DSPS is a common condition, particularly in adolescents and young adults. It is an important differential diagnosis for initial insomnia.

The mainstay of treatment is to advance the circadian rhythm using evening melatonin and morning light. The timing of both melatonin and light is critical.

An alternative treatment is chronotherapy, which involves progressively delaying sleep until the person is falling asleep and waking up at the desired time; however, once they are sleeping in phase, they may need melatonin and light to hold them in phase.

Some patients may choose professions that allow them to start work late and finish late, thus altering their lifestyle to fit their circadian rhythm. However, they should be aware that they may grow out of the DSPS with time.