Thank you, everybody, for your recent inquiries.  I’m happy to help!

The other day I was asked about daytime naps:  “is it better to take a nap when you are feeling really tired that day or try to go to bed earlier instead and skip the nap?”  In order to best answer the question, it’s important to know what is causing you to want or need the nap in the first place.

The science of sleep regulation is quite complex.  Sleep intensity is mediated by what is called the homeostatic mechanism of sleep, the specifics of which are beyond the scope of this blog entry.  Simply stated, the principles of sleep homeostasis dictate that sleep deprivation results in a compensating increase in intensity and duration of sleep, and excessive sleep (such as related to a daytime nap) reduces the inclination for sleep.  Taking a nap during the day implies daytime sleepiness, so let’s explore why one may be sleepy during the day.

One of the most common causes of daytime sleepiness is simple sleep deprivation.  If you’re getting 5 hours of sleep per night, for example, when your body needs 8, then likely you will not need to take a nap during the day any longer if you then gradually increase your sleep time to 8 hours per night, because by satisfying your body’s natural sleep needs consistently you should eventually feel substantially more awake and alert throughout the day.

Another common cause of daytime sleepiness is insomnia.  If you get less sleep at night because you’re awake a lot in bed, an obvious consequence would be feeling fatigued and drowsy during the day.  The problem is that taking a nap during the day can cause or worsen insomnia, particularly if the nap is prolonged and/or taken in the mid-afternoon to early evening; you tend to get a “second wind” and feel more awake and alert later than what you desire, resulting in further sleeplessness at night.

Finally, you could be sleepy during the day due to a problem with the quality (as opposed to the quantity) of your sleep.  Numerous sleep disorders can cause substantial drowsiness during the day even if you get your 8 hours per night:  obstructive sleep apnea, upper airway resistance syndrome, periodic limb movement disorder, and narcolepsy to name a few.  A good general rule to follow:  if you regularly get 7-8 hours of sleep per night and you’re consistently struggling to stay awake during the day when 7-8 hours per night used to satisfy your sleep need in the past, and if the sleepiness can’t be explained by some other factor (like medications or alcohol), you may want to see a specialist like me.

OK, synthesizing this down, then, here are my personal primary clinical concerns about napping:

1.  If you nap because you’re sleep deprived, there is often residual sleepiness between the time you awaken in the morning and the time your nap starts.

2.  If you nap due to insomnia, a vicious cycle can develop:  the nap can cause or worsen the insomnia, which then reduces your nocturnal total sleep time, which then makes you feel more sleepy during the day, which then makes you want to nap more.  In extreme cases people’s bedtime schedules can be completely turned around due to this problem, such that they become essentially nocturnal, sleeping throughout much of the day and remaining awake all night.

3.  Taking a nap to sustain you for the rest of day may “mask” concerns for an occult sleep disorder.

Bottom line here:  if the nap doesn’t cause difficulties falling or staying asleep at night, and if you don’t have substantial daytime fatigue or sleepiness prior to the nap, and if you’re confident you know the reason why you need the nap in the first place (such as staying up too late the night before), then I think there’s probably not much of a problem with taking that nap.  However, if you find yourself unable to stay awake during much of the day, if you are substantially sleepy during the day despite getting proper amounts of sleep, or if you are having mounting insomnia in this setting, there should be further concern about what is happening.

I’ll add several additional points before Sleep Help Desk closes for today.  First, naps can be intentional (i.e., laying down with the intention of taking a nap) or unintentional (such as falling asleep by accident in front of the television).  Second, if you doze off on the couch at 10 p.m. before you go to bed, that’s still a nap!  That late-night nap can cause difficulties falling back to sleep once you do go to bed, so try to avoid dozing off in the evening until you’re in bed intending to sleep.  Finally, to answer the original question posed to me above, I suggest not going to bed too early if you choose to not take the nap.  If you go to bed way earlier than usual, you can still have insomnia even if you’re sleep deprived, because your body clock “wants” regularity nonetheless.  The idea is to gradually increase your total sleep time such that you reliably get proper amounts of sleep every night.

Trivia question:  who is the famous person napping in the photograph above?  Write me with your answer!

Cheers, everyone!  Keep your questions coming!