I have a full toolbox of techniques for handling anxiety during the day, but nighttime is a little trickier. If you’ve had the same experience, you’re not just imagining things.
A Live Science article by Louise Bond examines this issue. According to Clinical Psychologist Charissa Chamorro, PhD, at night our brains have fewer distractions, leaving us more vulnerable to worries that creep in. This makes sense as we can redirect our attention during the day to activities that are not available when we’re in bed.

And you don’t need to be suffering from horrible anxiety for this to be the case. Research (Li et al., 2015, Int J Psychophysiol) showed that even among women without anxiety, fear was enhanced at nighttime, and not simply because of darkness, suggesting the involvement of the circadian rhythm. At the same time, as diurnal beings, humans naturally evolved to have stronger fear responses at night. This is partly due to the fact that we don’t see well in the absence of light and therefore are more vulnerable to nighttime predators.
Furthermore, while there is a natural ebb and flow of cortisol throughout the circadian cycle with cortisol levels peaking in the morning and being lowest at midnight, when anxiety keeps cortisol levels high during the day, that affects nighttime hormone release and therefore your ability to rest (Hirotsu et al., 2015, Sleep Sci).
To make matters worse, once your sleep is disrupted, worrying about your inability to get a good night’s sleep can result in being unable to sleep, and a vicious cycle develops.

You’ve probably heard the suggestions for improving sleep: turning the lights down in the evening, avoiding electronics (or using blue-light blockers), keeping your bedroom cool and dark, using a sound machine to mask noises, avoiding stressful or polarizing conversations in the evening, and the like.
To that I would add that what you do during the day itself can affect what kind of sleep you have at night. Meditation, practicing mindfulness, doing deep breathing exercises all put us into a calmer state. If you wake up in the middle of the night with a racing mind, having practiced and become adept at self-grounding techniques in daytime can help you soothe yourself at night.
While the roots of our anxiety may be complex, for those of us for whom it’s built up over time, so too will it take time to establish behaviors to help control it. Sometimes we need support of a therapist or medication, sometimes we can manage on our own, but setting aside time every day for even a short calming practice can help you improve management of anxiety no matter when it appears.
REFERENCES
Bond, Louise (2023) Can’t sleep? An expert reveals why anxiety may be worse at night. Live Science, https://www.livescience.com/anxiety-at-night
Li Y, Ma W, Kang Q, Qiao L, Tang D, Qiu J, Zhang Q, Li H (2015) Night or darkness, which intensifies the feeling of fear? Int J Psychophysiol, 97, 46-57. https://www.sciencedirect.com/science/article/abs/pii/S0167876015001713
Hirotsu, Tufik S, Anderson ML (2015) Interactions between sleep, stress, and metabolism: From physiological to pathological conditions. Sleep Sci, 8, 143-152. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4688585/pdf/main.pdf