Every hour of sleep before midnight is worth two after midnight. You have no doubt heard this from your parents when you were younger and probably even in the women’s magazines you read while you were waiting at the dentist last week. So is there any truth to this? Sleep experts have suggested that it is not as simple as hopping into bed at 7pm every night in order to get the best sleep, however there are benefits to getting to sleep before midnight.
Is there any difference between sleep before midnight and sleep after midnight?
Experts are now reporting that in fact yes, not all sleep is equal. To start we can look at the stages of sleep. Your sleep is composed of cycles- each approximately 90 minutes in length. Between these cycles an individual will alter between non- rapid eye movement (non-REM) sleep and REM sleep. REM sleep is the period in which you tend to dream and it is now thought that non-REM sleep could be a deeper more restorative sleep (1). Interestingly it is thought that throughout the night the ratio of each of these types of sleep tends to be altered. Studies have suggested that in the early parts of the night, non-REM sleep tends to be the dominant cycle whereas towards morning, REM sleep tends to take over (1,2,3). This is important as if non-REM sleep is deeper and more restorative, ensuring you get enough of it would be critical for sleep quality. Therefore hitting the hay at, say, 9pm will allow a greater amount of non-REM sleep compared to if you turn it in at 3am. Studies have also suggested that a lack of sleep and stress can result in an increase of cortisol in the evenings. Cortisol is supposed to be highest in the morning and then be low in the evenings allowing you a restful night sleep, therefore high cortisol in the evening can make it harder for you to get to sleep resulting in a vicious cycle which will have detrimental effects on your sleep (4, 5).
What is the recommendation?
In saying this there is a window between approximately 8pm to 12am where you can ensure that you get all the non-REM and REM sleep. One of the biggest things that experts recommend is trying to wake up at the same time every morning (1). This creates a pattern and may make it easier to get to sleep come night time.
The perfect time for each individual generally comes down to genetics. Some people are exhausted come 8pm and then up again at 5am, whereas others find they get their best work done in the evenings.
As long as you are in bed before midnight and are getting enough total hours of sleep you shouldn’t fight this as the best bedtime for you will be different to the next person (6). If you are not tired you shouldn’t force yourself to go to bed at 8pm as this can just result in you tossing and turning and staying up anyway. However, limiting stimulating activities at night can greatly improve your ability to get to sleep- but more on that at a later date!
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2. Hershner SD, Chervin RD. Causes and consequences of sleepiness among college students. Nature and Science of Sleep. 2014;6:73-84.
3. Brown RE, Basheer R, McKenna JT, Strecker RE, McCarley RW. CONTROL OF SLEEP AND WAKEFULNESS. Physiological reviews. 2012;92(3):1087-187.
4. Leproult R, Copinschi G, Buxton O, Van Cauter E. Sleep loss results in an elevation of cortisol levels the next evening. Sleep. 1997;20(10):865-70.
5. Spiegel K, Leproult R, L'Hermite-Baleriaux M, Copinschi G, Penev PD, Van Cauter E. Leptin levels are dependent on sleep duration: relationships with sympathovagal balance, carbohydrate regulation, cortisol, and thyrotropin. J Clin Endocrinol Metab. 2004;89(11):5762-71.
6. Thorn L, Hucklebridge F, Esgate A, Evans P, Clow A. The effect of dawn simulation on the cortisol response to awakening in healthy participants. Psychoneuroendocrinology. 2004;29(7):925-30.