Fatigue during the first trimester of pregnancy is likely caused by changing levels of hormones, such as progesterone. Toward the end of pregnancy, some women find it difficult to sleep because of the uncomfortable size of their abdomen. Some women are too excited, anxious, or worried about becoming mothers to sleep well. Other women who are pregnant complain that vivid dreams prevent them from getting restful sleep. Sleep apnea, especially if it's severe and causes your blood oxygen level to drop during sleep, is a risk to the fetus.
At the same time, it has been shown that memory consolidation in long-term memory (which depends on the hippocampus) occurs during NREM sleep.[29][33] This indicates that a decrease in the NREM sleep will result in less consolidation and therefore poorer memory performances in hippocampal-dependent long-term memory.[29][33] This drop in performance is one of the central symptoms of AD.[29]  

On the other hand, it is during sleep that beta-amyloid residues are degraded to prevent plaque formation.[29][30][32] It is the glymphatic system that is responsible for this and this phenomenon is called glymphatic clearance.[29][30][32] Thus, during wakefulness, the AB burden is greater because the metabolic activity and oxidative stress are higher and there is no degradation of the protein by the glymphatic clearance whereas during sleep, the burden will be smaller as there will be less metabolic activity and oxidative stress in addition to the glymphatic clearance that occurs at this time.[30][29]
What to do: Ask your doctor if your restless leg syndrome might be caused by another health condition or by a medication you're taking. Diabetes, arthritis, peripheral neuropathy, anemia, vitamin B deficiency, thyroid disease, and kidney problems can all contribute to restless leg syndrome. Medications that can cause restless leg syndrome as a side effect include antidepressants, antihistamines, and lithium. Treating the underlying condition or changing medications may banish the symptoms. Restless leg syndrome has been linked to deficiencies in iron and B vitamins, particularly folate, so talk to your doctor about boosting your intake of these nutrients.
The decrease in the quantity and quality of the NREM SWS as well as the disturbances of sleep will therefore increase the AB plaques.[29][30] This will first take place at the hippocampus level, from which memory is dependent.[29][30] This will result in cell death at this level and will contribute to diminished memory performances and cognitive decline found in AD disease.[29]

^ Hirshkowitz, Max (2004). "Chapter 10, Neuropsychiatric Aspects of Sleep and Sleep Disorders (pp 315-340)" (Google Books preview includes entire chapter 10). In Stuart C. Yudofsky; Robert E. Hales (eds.). Essentials of neuropsychiatry and clinical neurosciences (4 ed.). Arlington, Virginia, USA: American Psychiatric Publishing. ISBN 978-1-58562-005-0. ...insomnia is a symptom. It is neither a disease nor a specific condition. (from p. 322)
What to do: The best way to approach this issue is to try not to wake up in the first place. To do that, look at how often you're waking up and what's contributing to that. Men: Get your prostate checked, since inflammation of the prostate, benign prostatic hyperplasia (BPN), and prostate tumors can all cause this symptom. In women, frequent urination can go hand in hand with urinary issues such as incontinence , an overactive bladder, urinary tract infections, or cystitis. So see your doctor to be checked for these problems. Urinary tract problems, such as an overactive bladder, can be helped with Kegel exercises. Both men and women can learn these exercises to strengthen the muscles at the neck of the bladder.