I am a teacher, so I have to go to work early in the morning. I use a dawn simulator, and a light box, for 20 minutes in the morning when I first wake up. This maintains my ability to get up early and feel energetic during the day. However, because my job is demanding, I would like to sleep a few extra hours on the weekends. From experience, napping in the afternoon is a mistake as I feel groggy. Also, I know missing my regular wake up time is a big mistake. I would like to get up and do my regular light time, and then go back to sleep for a few hours. Would this seriously disturb my overall sleep pattern? I want the extra sleep but not at the expense of my mental wellbeing.

In general, it is best to maintain a regular bedtime, and wake up time, even on the weekends, to ensure you remain in sync with the environment. In your situation, however, we recommend a short nap of 30 minutes during the day: this restricted duration is restorative, yet produces minimal grogginess (“sleep inertia”) when you wake up.  Set your cellphone timer to alert you to get up, and don’t nap once evening approaches. If you do feel groggy after the nap, you could drink a caffeinated beverage immediately upon awakening.

How many hours should we sleep at night?

It depends on the individual. Six hours is around the short extreme, and nine hours is around the long extreme.  Most people fall somewhere in the middle.  How can you tell what’s right for you?  One clue is whether you feel work or family pressures are preventing you from going to bed, or staying in bed, when you’re sleepy.  The best measure, though, is if you feel alert throughout the day, stay in a reasonably good mood, and don’t oversleep on days off.  If you don’t do all three of these things, you should test whether a longer sleep interval — daily throughout the week — does the trick.  On the other end, some people allow themselves to sleep longer than they need, and they pay for this with low mood and fatigue during the day.  They often say to themselves, “If I could only sleep longer, I would have more energy the next day.” That may be a reasonable intuition, but it is a mistake.  Longer sleep than necessary can feed depression and a sense of exhaustion.

I have been using my light box for 30 minutes per day for 3 days in the morning and have noticed an increase in baseline anxiety. If i have baseline anxiety that seemed worse in the winter, is light therapy recommended or contraindicated?  I don’t have any history of hypomania. Should I stick it out for 2 more weeks and see if it resolves? Or do you recommend decreasing duration in front of lights to 15 minutes per day? At what point is light therapy contraindicated?

Another really good question.  First off, we want to emphasize a general point about clinical questions of this kind:  specific therapy  recommendations for a given individual in a given situation should come from one’s doctor and the ongoing treatment process.  As an educational website, our job is to provide general information about chronotherapy to the public.   The responses we provide are thus general, educational ones and should not be taken as clinical recommendations.  With that caveat, let me share some thoughts about this type of situation.
First, baseline anxiety is something that I pay a great deal of attention to as a clinician when I am considering any antidepressant treatment.  There is data that suggests that when depression is mixed with anxiety symptoms, the rate of antidepressant-induced manic response is heightened.  Even when there’s no past history of manic symptoms, antidepressants can sometimes activate and reveal underlying bipolar dispositions that were not evident.  Apart from the risk of treatment-induced mania, bright light therapy can cause or worsen ordinary (ie, not related to mania or bipolar disorder) anxiety as a side effect.
Second, I wasn’t clear about the nature of the diagnostic problem for which bright light therapy is being used here:  were you using light therapy for seasonal anxiety, for depression, for depression mixed with anxiety?  This would also have a bearing on how to manage your response to bright light therapy.
As a general rule, if someone that I am treating with bright light therapy experiences an increase in their anxiety, I would move to reduce and/or consider discontinuing the treatment.  The good news is that bright light therapy can be quickly and incrementally adjusted in several ways:  many light therapy lamps have a low and high lux option that allow for switching to a lower light intensity setting; the duration of exposure can be reduced; the distance from the light box can be increased; last, some studies suggest that light delivered later in the day, towards midday, causes less anxiety than early morning light.  So there are several, easy tweaks that can be done to reduce bright light therapy-induced anxiety.   The easy and rapid adjustability of treatments is a distinct characteristic and advantage of most chronotherapies.

How do I know if I am sensitive to the UV lights particularly with my eyes? I do not have any eye disorders, but I know I’m just a more sensitive person in general. Are there any eye or skin tests I could take before using the light therapy so I do not burn or damage my eyes or skin?

That’s a really good question!  Many people worry about the eye safety of bright light therapy.

You are absolutely correct to be concerned about UV light.  Light from this non-visible part of the spectrum can cause a variety of eye problems, especially macular degeneration.

The good news is that most, legitimate light boxes include a diffuser screen that is designed to entirely block out this portion of the wavelength.  This is another good reason to only use light boxes that have been clinically tested, both for effectiveness and safety.

I am 60 years old. For 16 years I have successfully treated my Seasonal Affective Disorder (SAD) with light therapy and a low dose of Paxil.  My first signs are anxiety, sleep disruption, and social withdrawal.  This year the light therapy is not working, and I am a mess from depression and anxiety.  Does light therapy become ineffective?  I have tried changes, and new, clinically approved lights, with no help.  Any thoughts?

Sorry to hear that you’ve been having trouble maintaining good effect from your light + medication regimen. There could be numerous reasons, unfortunately impossible to sort out from the limited information in your note.  You give one possible clue, however, when you mention “low dose of Paxil.” Both meds and light lie on dosing dimensions, which can be manipulated separately or in concert.  Dosing of light involves three main factors: level of illumination at the eyes (lux), duration of the daily session, and timing of the session relative to your circadian rhythm. Take (or re-take) our Morningness-Eveningness (AutoMEQ) questionnaire to see if your treatment schedule is a good match to your rhythm. Consider increasing session duration in modest steps of about 10 minutes, with four days at each step to ascertain effect.  You should not go beyond a 60-minute session.  Make sure your sitting position at the light box is correct for receiving full 10,000 lux exposure.  If your doctor is recommending a Paxil dose increase, it is very important to do this in coordination with light dose adjustment, or you may start experiencing side effects.

Loss of effect may also be due to progressive eye problems typical at your age, so you should have a thorough ophthalmology check-up, and you should discuss your experience with light dosing with your ophthalmologist. If these steps don’t produce results, it will be time to seek a psychiatry consultation to probe other factors that may have led to this year’s turnaround after your years-long positive experience.

Dr. Terman, I have read with great interest the summaries of your research, and some of your blog postings. I am wondering if you have ever come across patients whose sleep time and wake time are incredibly reliable, who don’t have a mood disorder, but who have an abnormally low afternoon dip? I have long had this problem — no issues with falling asleep, staying asleep, or waking up, but a dip after lunch that is so severe that I find myself walking across the street with my eyes closed. I am as perky as can be in the morning, but it is the most uncomfortable fight to try to stay awake in the afternoon. Nothing I have ever tried, other than an actual prescription stimulant, has had any effect, and I don’t like how I feel on the stimulant. I recently traveled to Israel, where I thought I’d be incredibly jet lagged, but, surprisingly, I felt far better than at home in the DC area. The only things I could think of were that it was so incredibly blindingly bright all day long every day, or that the time of my afternoon dip would literally have been while I was asleep because of the time change, and that my rhythms didn’t adjust in the week that I was there. I purchased a light box on the advice of my doctor, but I can’t find any information on how I should use it. I’m wondering if you’ve ever met anyone like me? It would be the greatest gift if I could have my afternoons, and not have to plan my days around needing a nap. Doctors have long told me that it’s healthy to take a nap, but it’s one thing to decide to take one, and it’s another to absolutely require one.

You had the correct insight.  The afternoon slump can occur with or without depression. If you measure the interval between the slump and the midpoint of nighttime sleep, they’re about 12 hours apart. (This is separate from the “post-prandial” slump some people experience after a heavy midday meal.)  You don’t need to spend all day in “blinding bright light” to counteract the slump.  The principle is to get to the light box as soon as you sense the onset of the slump, and not wait until it gets severe.  This can nip the slump in the bud, even with 10,000 lux light exposure as short as 10 minutes.  Some people will need longer, so you’ll need to experiment.  There are days when the slump comes a bit earlier or later, so don’t set the light session by the clock.  Rather, be attentive to the onset of the slump.  This technique works for many people, but not for everyone.  If it fails, and you have control of your work space, raising ambient light level in the afternoon to about 2000 lux – from ceiling or desk fixtures – including the light box – is another approach.  Don’t overdo it, however, or you may experience jitteriness, headache, eyestrain, or sudden mood shifts that interfere with work.

How do I know if I am sensitive to the UV lights particularly with my eyes? I do not have any eye disorders, but I know I’m just a more sensitive person in general. Are there any eye or skin tests I could take before using the light therapy so I do not burn or damage my eyes or skin?

That’s a really good question!  Many people worry about the eye safety of bright light therapy. You are absolutely correct to be concerned about UV light.  Light from this non-visible part of the spectrum can cause a variety of ocular problems, especially cataracts. The good news is that most, legitimate light boxes include a diffuser screen that is designed to entirely block out this wavelength portion. This is another good reason to only use light boxes that have been clinically tested, both for effectiveness and safety.

I’ve been using light therapy for SAD for about a month and have found it tremendously helpful for my mood. I suffered with SAD for about 6 months out of the year during winter for the past six years and just recently read Winter Blues by Rosenthal and realized that the 30 min I had stuck to for light therapy probably hadn’t been enough. I now do about an hour right when I wake up, and about an hour later sometime before 2 or 3 PM. Lately my body has been waking up between 4:30 (yikes!) and 5:45, which has not been great for me. I have shifted my bedtime earlier and I fall right asleep, but am tired of waking up so early and not being able to fall back asleep- and, I am okay with bed at 9:30 or 10, but don’t want to sleep earlier because then I miss so much of my evening, but since my body wakes me up so early, I am seriously exhausted by 8 PM. I’m 28 years old, active, and by 8 PM I feel like I’m 90 years old!!! Is there any way to alter my light therapy so that I can sleep in later? Try less or at a different time? Thanks for your help!

You are making a big mistake with self-treatment.  See Dr. Terman’s book, Reset Your Inner Clock, for a detailed explanation of setting light therapy parameters: duration of the session, timing of the session relative to your circadian (“inner”) clock, intensity of the light, sitting distance from the light box screen, and spectral quality (amount of blue in the white color mixture).  In a nutshell, you almost certainly have given yourself a light overdose by doubling the duration of exposure upon wake-up.  If 30 minute sessions were inadequate – which implies persistent, residual symptoms of depression – you might increase exposure duration in a series of small steps (such as 5 minutes), testing each step for three or four days before increasing it further.  A 60 minute exposure at 10,000 lux is virtually the maximum used in clinical practice, most often for patients who have not responded at all to shorter durations.  A major effect of such overdose is a large shift in the circadian clock to an earlier hour, resulting in premature awakening and evening sleepiness – just as you describe.  Adding another hour of light exposure later in the day is almost surely also excessive.  If you are slumping in the afternoon, a relatively short supplementary session – such as 10 or 15 minutes – is sufficient for most people to truncate the slump.

Can prolonged use of a light box cause eye sensitivity and headaches? I used a light box for about two years and developed these problems.

The answer is: not that we know of.  The symptoms you describe can certainly occur as short-term side effects, occurring during the use of a light box.   But there is no evidence of cumulative, prolonged or delayed ocular and/or headache effects from ordinary bright light therapy usage.  The combination of light sensitivity and light-aggravated headaches points in the possible direction of a migraine disorder.  We suggest consulting a neurologist.

My two year old goes to sleep between 7 and 7:30 pm, and often wakes up before 5 am. He usually takes a 2 hour nap. If he naps for less than 2 hours, we try for an earlier bedtime. Staying up later or going to bed earlier does not change his wake-up time. We have blackout shades plus blackout curtains in his room. He gets no illumination from sun at dawn, and after waking up he only gets artificial light because it’s still dark outside until about 7 am now. His pattern didn’t differ in the summer. I am following the standard advice such as putting him to bed while drowsy but still awake, but he still usually wakes before 5 am. Can any of the techniques on this website be useful for helping a toddler with early wakening?

It’s relatively difficult to answer such a question without knowing the patient, for example, the temperamental characteristics of the patient. It sounds as if he might be a morning type, which occurs frequently in toddlerhood, especially in children born preterm. I would suggest avoiding later diurnal naps, and trying to consolidate the nap, for example, between 1 and 2 pm. The parents can enrich the diet with nutrients rich in tryptophan, which is useful for sleep continuity.

At this moment I would not consider pharmacological treatment because we speak about a chronotype which can vary with age, and no diurnal consequences are reported about possible sleep restriction.

Eleven hours of sleep a day could be sufficient, following recently published recommendations from American Academy of Sleep Medicine (AASM) and the National Sleep Foundation.

More information on the AASM recommendations for pediatric populations is available here; more information on tryptophan is available here and here.