Insomnia (sleeplessness) or disturbed sleep (leading to tiredness and fatigue), may be partly due to the night sweats, control of which can lead to an improved sleep pattern, but insomnia has also been shown to be a menopausal symptom regardless of the presence of temperature changes and may begin a few years before the menopause.
Simple measures such as taking time to relax before going to bed by reading, watching television, or having a bath can make sure that you're not going to bed with your brain working overtime! Try to avoid caffeine or nicotine for at least 4 hours before bed time and don't have the bedroom too hot. Exercise during the day can help but don't exercise just before going to bed. Sometimes it actually helps to get up for a while, since lying and thinking about getting to sleep can make it harder to go off.
HRT has been shown to reduce insomnia and, because of the disruptive knock-on effects of lack of sleep, such as poor concentration, irritability and, of course, tiredness, some women choose to continue HRT purely for control of that symptom, even if they are not having flushes.
Some women find herbal drinks such as chamomile helpful, or sedative herbs such as valerian.